diff --git a/changes/3781.feature.rst b/changes/3781.feature.rst
new file mode 100644
index 0000000000..c3deba5489
--- /dev/null
+++ b/changes/3781.feature.rst
@@ -0,0 +1 @@
+Table and Tree widgets on desktop platforms will invoke `on_activate` when the Enter key is pressed and a single row/node is selected.
diff --git a/cocoa/src/toga_cocoa/widgets/table.py b/cocoa/src/toga_cocoa/widgets/table.py
index c73c086638..acd72bde07 100644
--- a/cocoa/src/toga_cocoa/widgets/table.py
+++ b/cocoa/src/toga_cocoa/widgets/table.py
@@ -2,6 +2,8 @@
 from travertino.size import at_least
 
 import toga
+from toga.keys import Key
+from toga_cocoa.keys import toga_key
 from toga_cocoa.libs import (
     NSBezelBorder,
     NSIndexSet,
@@ -125,9 +127,19 @@ def tableViewSelectionDidChange_(self, notification) -> None:
     @objc_method
     def onDoubleClick_(self, sender) -> None:
         clicked = self.interface.data[self.clickedRow]
-
         self.interface.on_activate(row=clicked)
 
+    @objc_method
+    def performKeyEquivalent_(self, event) -> bool:
+        if self.impl.has_focus:
+            key = toga_key(event)
+            if key["key"] in {Key.ENTER, Key.NUMPAD_ENTER} and not key["modifiers"]:
+                row = self.interface._selection_single
+                if row is not None:
+                    self.interface.on_activate(row=row)
+                    return True
+        return False
+
 
 class Table(Widget):
     def create(self):
@@ -172,6 +184,13 @@ def create(self):
         # Add the layout constraints
         self.add_constraints()
 
+    @property
+    def has_focus(self):
+        return (
+            self.native.window is not None
+            and self.native.window.firstResponder == self.native_table
+        )
+
     def change_source(self, source):
         self.native_table.reloadData()
 
diff --git a/cocoa/src/toga_cocoa/widgets/tree.py b/cocoa/src/toga_cocoa/widgets/tree.py
index 663997cc28..1e68b9a978 100644
--- a/cocoa/src/toga_cocoa/widgets/tree.py
+++ b/cocoa/src/toga_cocoa/widgets/tree.py
@@ -2,6 +2,8 @@
 from travertino.size import at_least
 
 import toga
+from toga.keys import Key
+from toga_cocoa.keys import toga_key
 from toga_cocoa.libs import (
     NSBezelBorder,
     NSIndexSet,
@@ -169,6 +171,17 @@ def onDoubleClick_(self, sender) -> None:
         node = self.itemAtRow(self.clickedRow).attrs["node"]
         self.interface.on_activate(node=node)
 
+    @objc_method
+    def performKeyEquivalent_(self, event) -> bool:
+        if self.impl.has_focus:
+            key = toga_key(event)
+            if key["key"] in {Key.ENTER, Key.NUMPAD_ENTER} and not key["modifiers"]:
+                node = self.interface._selection_single
+                if node is not None:
+                    self.interface.on_activate(node=node)
+                    return True
+        return False
+
 
 class Tree(Widget):
     def create(self):
@@ -216,6 +229,13 @@ def create(self):
         # Add the layout constraints
         self.add_constraints()
 
+    @property
+    def has_focus(self):
+        return (
+            self.native.window is not None
+            and self.native.window.firstResponder == self.native_tree
+        )
+
     def change_source(self, source):
         self.native_tree.reloadData()
 
diff --git a/cocoa/tests_backend/widgets/tree.py b/cocoa/tests_backend/widgets/tree.py
index 7bb972c939..304daf3a81 100644
--- a/cocoa/tests_backend/widgets/tree.py
+++ b/cocoa/tests_backend/widgets/tree.py
@@ -13,6 +13,7 @@
 class TreeProbe(SimpleProbe):
     native_class = NSScrollView
     supports_keyboard_shortcuts = True
+    supports_keyboard_boundary_shortcuts = False
     supports_widgets = True
 
     def __init__(self, widget):
@@ -184,3 +185,8 @@ async def activate_row(self, row_path):
             delay=0.1,
             clickCount=2,
         )
+
+    async def select_first_row_keyboard(self):
+        # Use the keyboard to ensure first row is selected.
+        await self.type_character("<down>")
+        await self.type_character("<up>")
diff --git a/core/src/toga/widgets/table.py b/core/src/toga/widgets/table.py
index 2f6ecb1d73..6512825ea7 100644
--- a/core/src/toga/widgets/table.py
+++ b/core/src/toga/widgets/table.py
@@ -174,6 +174,22 @@ def selection(self) -> list[Row] | Row | None:
         else:
             return self.data[selection]
 
+    @property
+    def _selection_single(self) -> Row | None:
+        """The currently selected row of the table.
+
+        Returns :any:`None` if no row is currently selected, or if multiple rows are
+        selected.
+        """
+        selection = self.selection
+        if self.multiple_select:
+            if len(selection) == 1:
+                return selection[0]
+            else:
+                return None
+        else:
+            return selection
+
     def scroll_to_top(self) -> None:
         """Scroll the view so that the top of the list (first row) is visible."""
         self.scroll_to_row(0)
diff --git a/core/src/toga/widgets/tree.py b/core/src/toga/widgets/tree.py
index 536b8bcb7a..251eb7f556 100644
--- a/core/src/toga/widgets/tree.py
+++ b/core/src/toga/widgets/tree.py
@@ -166,6 +166,22 @@ def selection(self) -> list[Node] | Node | None:
         """
         return self._impl.get_selection()
 
+    @property
+    def _selection_single(self) -> Node | None:
+        """The currently selected node of the tree.
+
+        Returns :any:`None` if no node is currently selected, or if multiple nodes are
+        selected.
+        """
+        selection = self.selection
+        if self.multiple_select:
+            if len(selection) == 1:
+                return selection[0]
+            else:
+                return None
+        else:
+            return selection
+
     def expand(self, node: Node | None = None) -> None:
         """Expand the specified node of the tree.
 
diff --git a/core/tests/widgets/test_table.py b/core/tests/widgets/test_table.py
index dadc19137b..76ac0c75d9 100644
--- a/core/tests/widgets/test_table.py
+++ b/core/tests/widgets/test_table.py
@@ -219,6 +219,7 @@ def test_single_selection(table, on_select_handler):
     """The current selection can be retrieved."""
     # Selection is initially empty
     assert table.selection is None
+    assert table._selection_single is None
     on_select_handler.assert_not_called()
 
     # Select an item
@@ -227,6 +228,9 @@ def test_single_selection(table, on_select_handler):
     # Selection returns a single row
     assert table.selection == table.data[1]
 
+    # _selection_single returns a single row
+    assert table._selection_single == table.data[1]
+
     # Selection handler was triggered
     on_select_handler.assert_called_once_with(table)
 
@@ -241,14 +245,31 @@ def test_multiple_selection(source, on_select_handler):
     )
     # Selection is initially empty
     assert table.selection == []
+    assert table._selection_single is None
     on_select_handler.assert_not_called()
 
     # Select an item
+    table._impl.simulate_selection([2])
+
+    # Selection returns a list of rows
+    assert table.selection == [table.data[2]]
+
+    # _selection_single a single item
+    assert table._selection_single is table.data[2]
+
+    # Selection handler was triggered
+    on_select_handler.assert_called_once_with(table)
+    on_select_handler.reset_mock()
+
+    # Select multiple items
     table._impl.simulate_selection([0, 2])
 
     # Selection returns a list of rows
     assert table.selection == [table.data[0], table.data[2]]
 
+    # _selection_single returns None
+    assert table._selection_single is None
+
     # Selection handler was triggered
     on_select_handler.assert_called_once_with(table)
 
diff --git a/core/tests/widgets/test_tree.py b/core/tests/widgets/test_tree.py
index 965d7e1a64..a0add3cde3 100644
--- a/core/tests/widgets/test_tree.py
+++ b/core/tests/widgets/test_tree.py
@@ -265,6 +265,7 @@ def test_single_selection(tree, on_select_handler):
     """The current selection can be retrieved."""
     # Selection is initially empty
     assert tree.selection is None
+    assert tree._selection_single is None
     on_select_handler.assert_not_called()
 
     # Select an item
@@ -273,6 +274,9 @@ def test_single_selection(tree, on_select_handler):
     # Selection returns a single row
     assert tree.selection == tree.data[0][1]
 
+    # _selection_single returns a single node
+    assert tree._selection_single == tree.data[0][1]
+
     # Selection handler was triggered
     on_select_handler.assert_called_once_with(tree)
 
@@ -287,14 +291,31 @@ def test_multiple_selection(source, on_select_handler):
     )
     # Selection is initially empty
     assert tree.selection == []
+    assert tree._selection_single is None
     on_select_handler.assert_not_called()
 
     # Select an item
+    tree._impl.simulate_selection([(1, 2, 1)])
+
+    # Selection returns a list of rows
+    assert tree.selection == [tree.data[1][2][1]]
+
+    # _selection_single returns a single item
+    assert tree._selection_single == tree.data[1][2][1]
+
+    # Selection handler was triggered
+    on_select_handler.assert_called_once_with(tree)
+    on_select_handler.reset_mock()
+
+    # Select multiple items
     tree._impl.simulate_selection([(0, 1), (1, 2, 1)])
 
     # Selection returns a list of rows
     assert tree.selection == [tree.data[0][1], tree.data[1][2][1]]
 
+    # _selection_single returns None
+    assert tree._selection_single is None
+
     # Selection handler was triggered
     on_select_handler.assert_called_once_with(tree)
 
diff --git a/gtk/tests_backend/widgets/tree.py b/gtk/tests_backend/widgets/tree.py
index ec9afcac4c..799804234c 100644
--- a/gtk/tests_backend/widgets/tree.py
+++ b/gtk/tests_backend/widgets/tree.py
@@ -104,3 +104,6 @@ async def activate_row(self, row_path):
             Gtk.TreePath(row_path),
             self.native_tree.get_columns()[0],
         )
+
+    async def select_first_row_keyboard(self):
+        pytest.skip("test not implemented for this platform")
diff --git a/testbed/tests/widgets/test_table.py b/testbed/tests/widgets/test_table.py
index adf3b2b6e3..3da8423cc2 100644
--- a/testbed/tests/widgets/test_table.py
+++ b/testbed/tests/widgets/test_table.py
@@ -92,13 +92,14 @@ async def headerless_probe(main_window, headerless_widget):
 
 
 @pytest.fixture
-async def multiselect_widget(source, on_select_handler):
+async def multiselect_widget(source, on_select_handler, on_activate_handler):
     skip_on_platforms("iOS")
     return toga.Table(
         ["A", "B", "C"],
         data=source,
         multiple_select=True,
         on_select=on_select_handler,
+        on_activate=on_activate_handler,
         style=Pack(flex=1),
     )
 
@@ -164,11 +165,15 @@ async def test_scroll(widget, probe):
     assert -100 < probe.scroll_position <= 0
 
 
-async def test_keyboard_navigation(widget, source, probe):
+async def test_keyboard_navigation(
+    widget, source, probe, on_select_handler, on_activate_handler
+):
     """The list can be navigated using a keyboard."""
     widget.focus()
 
     await probe.select_first_row_keyboard()
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
     await probe.redraw("First row selected")
     assert widget.selection == widget.data[0]
 
@@ -176,12 +181,25 @@ async def test_keyboard_navigation(widget, source, probe):
     await probe.type_character("a")
     await probe.redraw("Letter pressed - second row selected")
     assert widget.selection == widget.data[1]
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
     await probe.type_character("<down>")
     await probe.redraw("Down arrow pressed - third row selected")
     assert widget.selection == widget.data[2]
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
     await probe.type_character("a")
     await probe.redraw("Letter pressed - forth row selected")
     assert widget.selection == widget.data[3]
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
+
+    # Activate row
+    assert widget.selection == source[3]
+    await probe.type_character("\n")
+    await probe.redraw("Return key pressed - forth row activated")
+    on_activate_handler.assert_called_once_with(widget, row=source[3])
+    on_activate_handler.reset_mock()
 
     # Select the last item with the end key if supported then wrap around.
     if probe.supports_keyboard_boundary_shortcuts:
@@ -267,6 +285,31 @@ async def test_activate(
     on_activate_handler.reset_mock()
 
 
+async def test_activate_keyboard(
+    widget,
+    probe,
+    other,
+    other_probe,
+    source,
+    on_activate_handler,
+):
+    """Rows are activated by keyboard"""
+
+    widget.focus()
+    await probe.select_first_row_keyboard()
+
+    assert probe.has_focus
+    await probe.type_character("\n")
+    await probe.redraw("Return key pressed - first row is activated")
+    on_activate_handler.assert_called_once_with(widget, row=source[0])
+    on_activate_handler.reset_mock()
+
+    other.focus()
+    assert not probe.has_focus
+    await probe.type_character("\n")
+    on_activate_handler.assert_not_called()
+
+
 async def test_multiselect(
     multiselect_widget,
     multiselect_probe,
@@ -316,6 +359,7 @@ async def test_multiselect_keyboard_control(
     multiselect_probe,
     source,
     on_select_handler,
+    on_activate_handler,
 ):
     """Selection on a multiselect table can be controlled by keyboard.
 
@@ -333,14 +377,23 @@ async def test_multiselect_keyboard_control(
     # A single row can be added to the selection
     await multiselect_probe.select_first_row_keyboard()
     await multiselect_probe.redraw("First row selected")
+    on_select_handler.assert_called_once_with(multiselect_widget)
+    on_select_handler.reset_mock()
     assert multiselect_widget.selection == [source[0]]
 
+    # Activate row
+    await multiselect_probe.type_character("\n")
+    await multiselect_probe.redraw("Return key pressed - a single row is activated")
+    on_activate_handler.assert_called_once_with(multiselect_widget, row=source[0])
+    on_activate_handler.reset_mock()
+
+    # The selection can be extended
     await multiselect_probe.type_character("<down>", shift=True)
     await multiselect_probe.redraw(
         "Down arrow pressed - second row added to the selection"
     )
     assert multiselect_widget.selection == [source[0], source[1]]
-    on_select_handler.assert_called_with(multiselect_widget)
+    on_select_handler.assert_called_once_with(multiselect_widget)
     on_select_handler.reset_mock()
 
     await multiselect_probe.type_character("<down>", shift=True)
@@ -348,7 +401,7 @@ async def test_multiselect_keyboard_control(
         "Down arrow pressed - third row added to the selection"
     )
     assert multiselect_widget.selection == [source[0], source[1], source[2]]
-    on_select_handler.assert_called_with(multiselect_widget)
+    on_select_handler.assert_called_once_with(multiselect_widget)
     on_select_handler.reset_mock()
 
     await multiselect_probe.type_character("<up>", shift=True)
@@ -356,9 +409,18 @@ async def test_multiselect_keyboard_control(
         "Up arrow pressed - third row removed from the selection"
     )
     assert multiselect_widget.selection == [source[0], source[1]]
-    on_select_handler.assert_called_with(multiselect_widget)
+    on_select_handler.assert_called_once_with(multiselect_widget)
     on_select_handler.reset_mock()
 
+    # Activate is not fired when multiple rows are selected
+    assert len(multiselect_widget.selection) > 1
+    await multiselect_probe.type_character("\n")
+    await multiselect_probe.redraw(
+        "Return key pressed - multiple rows were selected - no activation"
+    )
+    on_activate_handler.assert_not_called()
+    on_activate_handler.reset_mock()
+
 
 class MyData:
     def __init__(self, text):
diff --git a/testbed/tests/widgets/test_tree.py b/testbed/tests/widgets/test_tree.py
index e8366c0c45..dd2f3a032a 100644
--- a/testbed/tests/widgets/test_tree.py
+++ b/testbed/tests/widgets/test_tree.py
@@ -139,7 +139,7 @@ async def headerless_probe(main_window, headerless_widget):
 
 
 @pytest.fixture
-def multiselect_widget(source, on_select_handler):
+def multiselect_widget(source, on_select_handler, on_activate_handler):
     # Although Android *has* a table implementation, it needs to be rebuilt.
     skip_on_platforms("iOS", "android", "windows")
     return toga.Tree(
@@ -147,6 +147,7 @@ def multiselect_widget(source, on_select_handler):
         data=source,
         multiple_select=True,
         on_select=on_select_handler,
+        on_activate=on_activate_handler,
         style=Pack(flex=1),
     )
 
@@ -474,6 +475,94 @@ async def test_activate(
     on_activate_handler.reset_mock()
 
 
+async def test_activate_keyboard(
+    widget,
+    probe,
+    other,
+    other_probe,
+    source,
+    on_activate_handler,
+):
+    """Rows are activated by keyboard"""
+
+    widget.focus()
+    await probe.select_first_row_keyboard()
+
+    assert probe.has_focus
+    await probe.type_character("\n")
+    await probe.redraw("Return key pressed - first row is activated")
+    on_activate_handler.assert_called_once_with(widget, node=source[0])
+    on_activate_handler.reset_mock()
+
+    other.focus()
+    assert not probe.has_focus
+    await probe.type_character("\n")
+    on_activate_handler.assert_not_called()
+
+
+async def test_keyboard_navigation(
+    widget, source, probe, on_select_handler, on_activate_handler
+):
+    """The list can be navigated using a keyboard."""
+    widget.focus()
+
+    await probe.select_first_row_keyboard()
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
+    await probe.redraw("First row selected")
+    assert widget.selection == widget.data[0]
+
+    # Navigate down with letter, arrow, letter.
+    await probe.type_character("a")
+    await probe.redraw("Letter pressed - second row selected")
+    assert widget.selection == widget.data[1]
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
+    await probe.type_character("<down>")
+    await probe.redraw("Down arrow pressed - third row selected")
+    assert widget.selection == widget.data[2]
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
+    await probe.type_character("a")
+    await probe.redraw("Letter pressed - forth row selected")
+    assert widget.selection == widget.data[3]
+    on_select_handler.assert_called_once_with(widget)
+    on_select_handler.reset_mock()
+
+    # Activate row
+    assert widget.selection == source[3]
+    await probe.type_character("\n")
+    await probe.redraw("Return key pressed - forth row selected")
+    on_activate_handler.assert_called_once_with(widget, node=source[3])
+    on_activate_handler.reset_mock()
+
+    # Select the last item with the end key if supported then wrap around.
+    if probe.supports_keyboard_boundary_shortcuts:
+        await probe.type_character("<end>")
+        await probe.redraw("Last row is selected")
+        assert widget.selection == widget.data[-1]
+        # Navigate by 1 item, wrapping around.
+        await probe.type_character("a")
+        await probe.redraw("Letter pressed - first row is selected")
+    else:
+        await probe.type_character("<up>")
+        await probe.type_character("<up>")
+        await probe.type_character("<up>")
+        await probe.redraw("Up arrow pressed thrice - first row is selected")
+    assert widget.selection == widget.data[0]
+
+    # Type a letter that no items start with to verify the selection doesn't change.
+    await probe.type_character("x")
+    await probe.redraw("Invalid letter pressed - first row is still selected")
+    assert widget.selection == widget.data[0]
+
+    # clear the table and verify with an empty selection.
+    widget.data.clear()
+    await probe.type_character("a")
+    await probe.redraw("Letter pressed - no row selected")
+    assert not widget.selection
+
+
 async def test_multiselect(
     multiselect_widget,
     multiselect_probe,
@@ -524,6 +613,72 @@ async def test_multiselect(
         assert len(multiselect_widget.selection) == 70
 
 
+async def test_multiselect_keyboard_control(
+    multiselect_widget,
+    multiselect_probe,
+    source,
+    on_select_handler,
+    on_activate_handler,
+):
+    """Selection on a multiselect table can be controlled by keyboard.
+
+    Keyboard navigation can produce different events to mouse navigation,
+    so we need to test keyboard selection independent of mouse selection.
+    """
+    await multiselect_probe.redraw("No row is selected in multiselect table")
+
+    # Initial selection is empty
+    assert multiselect_widget.selection == []
+    on_select_handler.assert_not_called()
+
+    multiselect_widget.focus()
+
+    # A single row can be added to the selection
+    await multiselect_probe.select_first_row_keyboard()
+    await multiselect_probe.redraw("First row selected")
+    on_select_handler.assert_called_once_with(multiselect_widget)
+    on_select_handler.reset_mock()
+    assert multiselect_widget.selection == [source[0]]
+
+    # Activate row
+    await multiselect_probe.type_character("\n")
+    await multiselect_probe.redraw("Return key pressed - a single row is selected")
+    on_activate_handler.assert_called_once_with(multiselect_widget, node=source[0])
+    on_activate_handler.reset_mock()
+
+    # The selection can be extended
+    await multiselect_probe.type_character("<down>", shift=True)
+    await multiselect_probe.redraw(
+        "Down arrow pressed - second row added to the selection"
+    )
+    assert multiselect_widget.selection == [source[0], source[1]]
+    on_select_handler.assert_called_once_with(multiselect_widget)
+    on_select_handler.reset_mock()
+
+    await multiselect_probe.type_character("<down>", shift=True)
+    await multiselect_probe.redraw(
+        "Down arrow pressed - third row added to the selection"
+    )
+    assert multiselect_widget.selection == [source[0], source[1], source[2]]
+    on_select_handler.assert_called_once_with(multiselect_widget)
+    on_select_handler.reset_mock()
+
+    await multiselect_probe.type_character("<up>", shift=True)
+    await multiselect_probe.redraw(
+        "Up arrow pressed - third row removed from the selection"
+    )
+    assert multiselect_widget.selection == [source[0], source[1]]
+    on_select_handler.assert_called_once_with(multiselect_widget)
+    on_select_handler.reset_mock()
+
+    # Activate is not fired when multiple rows are selected
+    assert len(multiselect_widget.selection) > 1
+    await multiselect_probe.type_character("\n")
+    await multiselect_probe.redraw("Return key pressed - multiple rows selected")
+    on_activate_handler.assert_not_called()
+    on_activate_handler.reset_mock()
+
+
 class MyData:
     def __init__(self, text):
         self.text = text
diff --git a/winforms/src/toga_winforms/widgets/table.py b/winforms/src/toga_winforms/widgets/table.py
index 20aba42bc0..7c14db2001 100644
--- a/winforms/src/toga_winforms/widgets/table.py
+++ b/winforms/src/toga_winforms/widgets/table.py
@@ -72,6 +72,7 @@ def create(self):
 
     def add_action_events(self):
         self.native.MouseDoubleClick += WeakrefCallable(self.winforms_double_click)
+        self.native.KeyPress += WeakrefCallable(self.winforms_key_press)
 
     def set_bounds(self, x, y, width, height):
         super().set_bounds(x, y, width, height)
@@ -180,6 +181,13 @@ def winforms_double_click(self, sender, e):
             # that isn't guaranteed by the documentation.
             pass
 
+    def winforms_key_press(self, sender, e):
+        if ord(e.KeyChar) == int(WinForms.Keys.Enter):
+            row = self.interface._selection_single
+            if row:
+                self.interface.on_activate(row=row)
+                e.Handled = True
+
     def _create_column(self, heading, accessor):
         col = WinForms.ColumnHeader()
         col.Text = heading