diff --git a/CHANGELOG.md b/CHANGELOG.md
index e69de29bb2d..0e71b404de7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -0,0 +1 @@
+- Support loading Firebase Functions packaged as an ES module. (#3485)
diff --git a/src/deploy/functions/runtimes/node/triggerParser.js b/src/deploy/functions/runtimes/node/triggerParser.js
index 0a488027ff5..ff1bdd26baf 100644
--- a/src/deploy/functions/runtimes/node/triggerParser.js
+++ b/src/deploy/functions/runtimes/node/triggerParser.js
@@ -7,7 +7,28 @@ var EXIT = function () {
   process.exit(0);
 };
 
-(function () {
+/**
+ * Dynamically load import function to prevent TypeScript from
+ * transpiling into a require.
+ *
+ * See https://github.com/microsoft/TypeScript/issues/43329.
+ */
+// eslint-disable-next-line @typescript-eslint/no-implied-eval
+const dynamicImport = new Function("modulePath", "return import(modulePath)");
+
+async function loadModule(packageDir) {
+  try {
+    return require(packageDir);
+  } catch (e) {
+    if (e.code === "ERR_REQUIRE_ESM") {
+      const mod = await dynamicImport(require.resolve(packageDir));
+      return mod;
+    }
+    throw e;
+  }
+}
+
+(async function () {
   if (!process.send) {
     console.warn("Could not parse function triggers (process.send === undefined).");
     process.exit(1);
@@ -23,7 +44,7 @@ var EXIT = function () {
   var mod;
   var triggers = [];
   try {
-    mod = require(packageDir);
+    mod = await loadModule(packageDir);
   } catch (e) {
     if (e.code === "MODULE_NOT_FOUND") {
       process.send(
diff --git a/src/emulator/functionsEmulatorRuntime.ts b/src/emulator/functionsEmulatorRuntime.ts
index ac4e98842de..9b99530e9a9 100644
--- a/src/emulator/functionsEmulatorRuntime.ts
+++ b/src/emulator/functionsEmulatorRuntime.ts
@@ -27,6 +27,15 @@ import * as _ from "lodash";
 let triggers: EmulatedTriggerMap | undefined;
 let developerPkgJSON: PackageJSON | undefined;
 
+/**
+ * Dynamically load import function to prevent TypeScript from
+ * transpiling into a require.
+ *
+ * See https://github.com/microsoft/TypeScript/issues/43329.
+ */
+// eslint-disable-next-line @typescript-eslint/no-implied-eval
+const dynamicImport = new Function("modulePath", "return import(modulePath)");
+
 function isFeatureEnabled(
   frb: FunctionsRuntimeBundle,
   feature: keyof FunctionsRuntimeFeatures
@@ -567,6 +576,7 @@ async function initializeFirebaseAdminStubs(frb: FunctionsRuntimeBundle): Promis
   // Stub the admin module in the require cache
   require.cache[adminResolution.resolution] = {
     exports: proxiedAdminModule,
+    path: path.dirname(adminResolution.resolution),
   };
 
   logDebug("firebase-admin has been stubbed.", {
@@ -776,6 +786,7 @@ async function initializeFunctionsConfigHelper(frb: FunctionsRuntimeBundle): Pro
   // Stub the functions module in the require cache
   require.cache[functionsResolution.resolution] = {
     exports: proxiedFunctionsModule,
+    path: path.dirname(functionsResolution.resolution),
   };
 
   logDebug("firebase-functions has been stubbed.", {
@@ -1065,8 +1076,12 @@ async function initializeRuntime(
     try {
       triggerModule = require(frb.cwd);
     } catch (err) {
-      await moduleResolutionDetective(frb, err);
-      return;
+      if (err.code !== "ERR_REQUIRE_ESM") {
+        await moduleResolutionDetective(frb, err);
+        return;
+      }
+      // tslint:disable:no-unsafe-assignment
+      triggerModule = await dynamicImport(require.resolve(frb.cwd));
     }
   }
   if (extensionTriggers) {