diff --git a/js/web/script/test-runner-cli.ts b/js/web/script/test-runner-cli.ts
index d56792c6e3..9105c02412 100644
--- a/js/web/script/test-runner-cli.ts
+++ b/js/web/script/test-runner-cli.ts
@@ -12,6 +12,7 @@ import * as os from 'os';
 import * as path from 'path';
 import {inspect} from 'util';
 
+import {onnx} from '../lib/onnxjs/ort-schema/protobuf/onnx';
 import {bufferToBase64} from '../test/test-shared';
 import {Test} from '../test/test-types';
 
@@ -264,10 +265,12 @@ async function main() {
 
     let modelUrl: string|null = null;
     let cases: Test.ModelTestCase[] = [];
+    let externalData: Array<{data: string; path: string}>|undefined;
 
     npmlog.verbose('TestRunnerCli.Init.Model', `Start to prepare test data from folder: ${testDataRootFolder}`);
 
     try {
+      const maybeExternalDataFiles: Array<[fileNameWithoutExtension: string, size: number]> = [];
       for (const thisPath of fs.readdirSync(testDataRootFolder)) {
         const thisFullPath = path.join(testDataRootFolder, thisPath);
         const stat = fs.lstatSync(thisFullPath);
@@ -282,6 +285,8 @@ async function main() {
             } else {
               throw new Error('there are multiple model files under the folder specified');
             }
+          } else {
+            maybeExternalDataFiles.push([path.parse(thisPath).name, stat.size]);
           }
         } else if (stat.isDirectory()) {
           const dataFiles: string[] = [];
@@ -307,6 +312,34 @@ async function main() {
       if (modelUrl === null) {
         throw new Error('there are no model file under the folder specified');
       }
+      // for performance consideration, we do not parse every model. when we think it's likely to have external
+      // data, we will parse it. We think it's "likely" when one of the following conditions is met:
+      // 1. any file in the same folder has the similar file name as the model file
+      //    (e.g., model file is "model_abc.onnx", and there is a file "model_abc.pb" or "model_abc.onnx.data")
+      // 2. the file size is larger than 1GB
+      const likelyToHaveExternalData = maybeExternalDataFiles.some(
+          ([fileNameWithoutExtension, size]) =>
+              path.basename(modelUrl!).startsWith(fileNameWithoutExtension) || size >= 1 * 1024 * 1024 * 1024);
+      if (likelyToHaveExternalData) {
+        const model = onnx.ModelProto.decode(fs.readFileSync(path.join(testDataRootFolder, path.basename(modelUrl!))));
+        const externalDataPathSet = new Set<string>();
+        for (const initializer of model.graph!.initializer!) {
+          if (initializer.externalData) {
+            for (const data of initializer.externalData) {
+              if (data.key === 'location') {
+                externalDataPathSet.add(data.value!);
+              }
+            }
+          }
+        }
+        externalData = [];
+        const externalDataPaths = [...externalDataPathSet];
+        for (const dataPath of externalDataPaths) {
+          const fullPath = path.resolve(testDataRootFolder, dataPath);
+          const url = path.join(TEST_DATA_BASE, path.relative(TEST_ROOT, fullPath));
+          externalData.push({data: url, path: dataPath});
+        }
+      }
     } catch (e) {
       npmlog.error('TestRunnerCli.Init.Model', `Failed to prepare test data. Error: ${inspect(e)}`);
       throw e;
@@ -340,9 +373,23 @@ async function main() {
     npmlog.verbose('TestRunnerCli.Init.Model', ` Model file: ${modelUrl}`);
     npmlog.verbose('TestRunnerCli.Init.Model', ` Backend: ${backend}`);
     npmlog.verbose('TestRunnerCli.Init.Model', ` Test set(s): ${cases.length} (${caseCount})`);
+    if (externalData) {
+      npmlog.verbose('TestRunnerCli.Init.Model', ` External data: ${externalData.length}`);
+      for (const data of externalData) {
+        npmlog.verbose('TestRunnerCli.Init.Model', `  - ${data.path}`);
+      }
+    }
     npmlog.verbose('TestRunnerCli.Init.Model', '===============================================================');
 
-    return {name: path.basename(testDataRootFolder), platformCondition, modelUrl, backend, cases, ioBinding};
+    return {
+      name: path.basename(testDataRootFolder),
+      platformCondition,
+      modelUrl,
+      backend,
+      cases,
+      ioBinding,
+      externalData
+    };
   }
 
   function tryLocateModelTestFolder(searchPattern: string): string {
diff --git a/js/web/test/test-runner.ts b/js/web/test/test-runner.ts
index 442cb1bcf1..b01d474788 100644
--- a/js/web/test/test-runner.ts
+++ b/js/web/test/test-runner.ts
@@ -138,8 +138,8 @@ async function loadTensors(
 
 async function initializeSession(
     modelFilePath: string, backendHint: ort.InferenceSession.ExecutionProviderConfig, ioBindingMode: Test.IOBindingMode,
-    profile: boolean, sessionOptions: ort.InferenceSession.SessionOptions,
-    fileCache?: FileCacheBuffer): Promise<ort.InferenceSession> {
+    profile: boolean, externalData: ort.InferenceSession.SessionOptions['externalData'],
+    sessionOptions: ort.InferenceSession.SessionOptions, fileCache?: FileCacheBuffer): Promise<ort.InferenceSession> {
   const preloadModelData: Uint8Array|undefined =
       fileCache && fileCache[modelFilePath] ? fileCache[modelFilePath] : undefined;
   Logger.verbose(
@@ -153,7 +153,8 @@ async function initializeSession(
     executionProviders: [backendHint],
     profiler: profilerConfig,
     enableProfiling: profile,
-    preferredOutputLocation: ioBindingMode === 'gpu-location' ? ('gpu-buffer' as const) : undefined
+    preferredOutputLocation: ioBindingMode === 'gpu-location' ? ('gpu-buffer' as const) : undefined,
+    externalData
   };
 
   let session: ort.InferenceSession;
@@ -246,8 +247,8 @@ export class ModelTestContext {
       const executionProviderConfig =
           modelTest.backend === 'webnn' ? (testOptions?.webnnOptions || 'webnn') : modelTest.backend!;
       const session = await initializeSession(
-          modelTest.modelUrl, executionProviderConfig, modelTest.ioBinding, profile, testOptions?.sessionOptions || {},
-          this.cache);
+          modelTest.modelUrl, executionProviderConfig, modelTest.ioBinding, profile, modelTest.externalData,
+          testOptions?.sessionOptions || {}, this.cache);
 
       const initEnd = now();
 
diff --git a/js/web/test/test-types.ts b/js/web/test/test-types.ts
index cd008e82e5..14b9fd7c00 100644
--- a/js/web/test/test-types.ts
+++ b/js/web/test/test-types.ts
@@ -65,6 +65,7 @@ export declare namespace Test {
   export interface ModelTest {
     name: string;
     modelUrl: string;
+    externalData?: InferenceSession.SessionOptions['externalData'];
     backend?: string;  // value should be populated at build time
     ioBinding: IOBindingMode;
     platformCondition?: PlatformCondition;