diff --git a/src/client/createSorokitClient.ts b/src/client/createSorokitClient.ts
index acffbb5..ce4556c 100644
--- a/src/client/createSorokitClient.ts
+++ b/src/client/createSorokitClient.ts
@@ -128,6 +128,12 @@ export interface SorokitClientConfig {
    * @deprecated Prefer `logLevel: "debug"`
    */
   debug?: boolean;
+  /**
+   * Prefix for built-in console log lines. Defaults to `"[sorokit]"`.
+   * Use distinct values (e.g. `"[sorokit:testnet]"`) when running multiple clients.
+   * Ignored when a custom `logger` is provided.
+   */
+  logPrefix?: string;
   /** Custom logger — overrides the built-in console logger */
   logger?: SorokitLogger;
   /**
@@ -534,6 +540,7 @@ export function createSorokitClient(
     config.logger ??
     createLogger({
       logLevel: config.logLevel ?? (config.debug ? "debug" : "off"),
+      ...(config.logPrefix !== undefined ? { prefix: config.logPrefix } : {}),
     });
   const logger = createTracedLogger(baseLogger, { traceId });
 
diff --git a/src/shared/logger.ts b/src/shared/logger.ts
index 658d435..e955cb3 100644
--- a/src/shared/logger.ts
+++ b/src/shared/logger.ts
@@ -20,6 +20,12 @@ export interface LoggerOptions {
   logLevel?: LogLevel;
   debug?: boolean;
   logger?: SorokitLogger;
+  /**
+   * Prefix prepended to every console log line for the built-in logger.
+   * Defaults to `"[sorokit]"`. Ignored when a custom `logger` is provided.
+   * Useful for distinguishing multiple client instances (e.g. `"[sorokit:testnet]"`).
+   */
+  prefix?: string;
 }
 
 const LOG_LEVEL_PRIORITY: Record<LogLevel, number> = {
@@ -60,12 +66,36 @@ export function sanitizeLogMeta(meta?: StructuredLogMeta): StructuredLogMeta | u
   return sanitized;
 }
 
-function createConsoleLogger(): SorokitLogger {
+function createConsoleLogger(prefix = "[sorokit]"): SorokitLogger {
   return {
-    debug: (message, meta) => console.debug("[sorokit]", { level: "debug", message, ...meta, timestamp: new Date().toISOString() }),
-    info: (message, meta) => console.info("[sorokit]", { level: "info", message, ...meta, timestamp: new Date().toISOString() }),
-    warn: (message, meta) => console.warn("[sorokit]", { level: "warn", message, ...meta, timestamp: new Date().toISOString() }),
-    error: (message, meta) => console.error("[sorokit]", { level: "error", message, ...meta, timestamp: new Date().toISOString() }),
+    debug: (message, meta) =>
+      console.debug(prefix, {
+        level: "debug",
+        message,
+        ...meta,
+        timestamp: new Date().toISOString(),
+      }),
+    info: (message, meta) =>
+      console.info(prefix, {
+        level: "info",
+        message,
+        ...meta,
+        timestamp: new Date().toISOString(),
+      }),
+    warn: (message, meta) =>
+      console.warn(prefix, {
+        level: "warn",
+        message,
+        ...meta,
+        timestamp: new Date().toISOString(),
+      }),
+    error: (message, meta) =>
+      console.error(prefix, {
+        level: "error",
+        message,
+        ...meta,
+        timestamp: new Date().toISOString(),
+      }),
   };
 }
 
@@ -103,7 +133,8 @@ function createLevelLogger(level: LogLevel, sink: SorokitLogger): SorokitLogger
 export function createLogger(options?: LoggerOptions): SorokitLogger {
   const level: LogLevel = options?.logLevel ?? (options?.debug ? "debug" : "off");
   if (level === "off") return createNoopLogger();
-  return createLevelLogger(level, options?.logger ?? createConsoleLogger());
+  const sink = options?.logger ?? createConsoleLogger(options?.prefix);
+  return createLevelLogger(level, sink);
 }
 
 /** Add trace identifiers to all entries emitted by a logger. */
diff --git a/src/tests/logger.test.ts b/src/tests/logger.test.ts
index 39d152a..dedcedf 100644
--- a/src/tests/logger.test.ts
+++ b/src/tests/logger.test.ts
@@ -93,6 +93,28 @@ describe("shared/logger", () => {
 
       infoSpy.mockRestore();
     });
+
+    it("applies a custom prefix to console output (#257)", () => {
+      const debugSpy = vi
+        .spyOn(console, "debug")
+        .mockImplementation(() => undefined);
+      const logger = createLogger({
+        logLevel: "debug",
+        prefix: "[sorokit:testnet]",
+      });
+
+      logger.debug("prefixed");
+
+      expect(debugSpy).toHaveBeenCalledWith(
+        "[sorokit:testnet]",
+        expect.objectContaining({
+          level: "debug",
+          message: "prefixed",
+        }),
+      );
+
+      debugSpy.mockRestore();
+    });
   });
 
   describe("withLogging", () => {
@@ -157,6 +179,43 @@ describe("createSorokitClient logger integration", () => {
     );
   });
 
+  it("uses logPrefix in console output when debug is enabled (#257)", () => {
+    const debugSpy = vi
+      .spyOn(console, "debug")
+      .mockImplementation(() => undefined);
+
+    const result = createSorokitClient({
+      network: "testnet",
+      debug: true,
+      logPrefix: "[app:testnet]",
+      cache: {
+        get: () => undefined,
+        set: () => undefined,
+        invalidate: () => undefined,
+        clear: () => undefined,
+      },
+    });
+
+    expect(result.status).toBe("ok");
+    // client.create emits info; cache probe emits debug — both use logPrefix
+    expect(consoleInfoSpy).toHaveBeenCalledWith(
+      "[app:testnet]",
+      expect.objectContaining({
+        operation: "client.create",
+        status: "ok",
+        network: "testnet",
+      }),
+    );
+    expect(debugSpy).toHaveBeenCalledWith(
+      "[app:testnet]",
+      expect.objectContaining({
+        message: "client.create: checked cache for recovered wallet state",
+      }),
+    );
+
+    debugSpy.mockRestore();
+  });
+
   it("does not log wallet.emptyState calls", () => {
     const { logger: custom, calls } = createCapturingLogger();
     const result = createSorokitClient({