diff --git a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/CertificatePinner.kt b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/CertificatePinner.kt
index 925502aceacb..3996bd10025e 100644
--- a/okhttp/src/commonJvmAndroid/kotlin/okhttp3/CertificatePinner.kt
+++ b/okhttp/src/commonJvmAndroid/kotlin/okhttp3/CertificatePinner.kt
@@ -290,8 +290,14 @@ class CertificatePinner internal constructor(
       }
     }
 
-    fun matchesHostname(hostname: String): Boolean =
-      when {
+    fun matchesHostname(hostname: String): Boolean {
+      // A hostname may carry a trailing dot for an absolute DNS name -- ConnectPlan derives it
+      // from address.url.host, which explicitly preserves one. A pin's pattern is
+      // developer-authored and never has one, so without this normalization the pin is silently
+      // skipped against the dotted spelling of an otherwise-identical hostname.
+      // OkHostnameVerifier already treats both spellings as equivalent for the same reason.
+      val hostname = if (hostname.endsWith(".")) hostname.dropLast(1) else hostname
+      return when {
         pattern.startsWith("**.") -> {
           // With ** empty prefixes match so exclude the dot from regionMatches().
           val suffixLength = pattern.length - 3
@@ -312,6 +318,7 @@ class CertificatePinner internal constructor(
           hostname == pattern
         }
       }
+    }
 
     fun matchesCertificate(certificate: X509Certificate): Boolean =
       when (hashAlgorithm) {
diff --git a/okhttp/src/jvmTest/kotlin/okhttp3/CertificatePinnerKotlinTest.kt b/okhttp/src/jvmTest/kotlin/okhttp3/CertificatePinnerKotlinTest.kt
index 4a48ac813436..d6cf32d1fb7f 100644
--- a/okhttp/src/jvmTest/kotlin/okhttp3/CertificatePinnerKotlinTest.kt
+++ b/okhttp/src/jvmTest/kotlin/okhttp3/CertificatePinnerKotlinTest.kt
@@ -180,6 +180,23 @@ class CertificatePinnerKotlinTest {
     assertFalse(pin.matchesHostname("www.example.com"))
   }
 
+  @Test fun testMatchesHostnameWithTrailingDot() {
+    // https://github.com/lysine-dev/okhttp/issues/9724
+    val exactPin = Pin("example.com", certA1Sha256Pin)
+    assertTrue(exactPin.matchesHostname("example.com"))
+    assertTrue(exactPin.matchesHostname("example.com."))
+
+    val wildcardPin = Pin("*.example.com", certA1Sha256Pin)
+    assertTrue(wildcardPin.matchesHostname("a.example.com"))
+    assertTrue(wildcardPin.matchesHostname("a.example.com."))
+
+    val certificatePinner =
+      CertificatePinner.Builder()
+        .add("example.com", certA1Sha256Pin)
+        .build()
+    assertThat(certificatePinner.findMatchingPins("example.com.")).containsExactly(exactPin)
+  }
+
   @Test fun testMatchesSha256() {
     val pin = Pin("example.com", certA1Sha256Pin)
     assertTrue(pin.matchesCertificate(certA1.certificate))