diff --git a/lib/internal/source_map/source_map_cache.js b/lib/internal/source_map/source_map_cache.js
index dfb42f83f6f1b1..ea87a579636671 100644
--- a/lib/internal/source_map/source_map_cache.js
+++ b/lib/internal/source_map/source_map_cache.js
@@ -155,6 +155,9 @@ function maybeCacheSourceMap(filename, content, moduleInstance, isGeneratedSourc
   }
 
   const data = dataFromUrl(filename, sourceMapURL);
+  // `data` could be null if the source map is invalid.
+  // In this case, create a cache entry with null data with source url for test coverage.
+
   const entry = {
     __proto__: null,
     lineLengths: lineLengths(content),
@@ -277,6 +280,8 @@ function sourceMapFromDataUrl(sourceURL, url) {
       const parsedData = JSONParse(decodedData);
       return sourcesToAbsolute(sourceURL, parsedData);
     } catch (err) {
+      // TODO(legendecas): warn about invalid source map JSON string.
+      // But it could be verbose.
       debug(err);
       return null;
     }
@@ -331,24 +336,38 @@ function sourceMapCacheToObject() {
 
 /**
  * Find a source map for a given actual source URL or path.
+ *
+ * This function may be invoked from user code or test runner, this must not throw
+ * any exceptions.
  * @param {string} sourceURL - actual source URL or path
  * @returns {import('internal/source_map/source_map').SourceMap | undefined} a source map or undefined if not found
  */
 function findSourceMap(sourceURL) {
-  if (RegExpPrototypeExec(kLeadingProtocol, sourceURL) === null) {
-    sourceURL = pathToFileURL(sourceURL).href;
+  if (typeof sourceURL !== 'string') {
+    return undefined;
   }
+
   SourceMap ??= require('internal/source_map/source_map').SourceMap;
-  const entry = getModuleSourceMapCache().get(sourceURL) ?? generatedSourceMapCache.get(sourceURL);
-  if (entry === undefined) {
+  try {
+    if (RegExpPrototypeExec(kLeadingProtocol, sourceURL) === null) {
+      // If the sourceURL is an invalid path, this will throw an error.
+      sourceURL = pathToFileURL(sourceURL).href;
+    }
+    const entry = getModuleSourceMapCache().get(sourceURL) ?? generatedSourceMapCache.get(sourceURL);
+    if (entry?.data == null) {
+      return undefined;
+    }
+
+    let sourceMap = entry.sourceMap;
+    if (sourceMap === undefined) {
+      sourceMap = new SourceMap(entry.data, { lineLengths: entry.lineLengths });
+      entry.sourceMap = sourceMap;
+    }
+    return sourceMap;
+  } catch (err) {
+    debug(err);
     return undefined;
   }
-  let sourceMap = entry.sourceMap;
-  if (sourceMap === undefined) {
-    sourceMap = new SourceMap(entry.data, { lineLengths: entry.lineLengths });
-    entry.sourceMap = sourceMap;
-  }
-  return sourceMap;
 }
 
 module.exports = {
diff --git a/test/parallel/test-runner-source-maps-invalid-json.js b/test/parallel/test-runner-source-maps-invalid-json.js
new file mode 100644
index 00000000000000..508e2d432117f7
--- /dev/null
+++ b/test/parallel/test-runner-source-maps-invalid-json.js
@@ -0,0 +1,12 @@
+// Flags: --enable-source-maps
+'use strict';
+
+require('../common');
+const test = require('node:test');
+
+// Verify that test runner can handle invalid source maps.
+
+test('ok', () => {});
+
+// eslint-disable-next-line @stylistic/js/spaced-comment
+//# sourceMappingURL=data:application/json;base64,-1