diff --git a/packages/babel-plugin-transform-typescript/package.json b/packages/babel-plugin-transform-typescript/package.json
index c5fcbf6050..65fa06be74 100644
--- a/packages/babel-plugin-transform-typescript/package.json
+++ b/packages/babel-plugin-transform-typescript/package.json
@@ -26,7 +26,9 @@
   },
   "devDependencies": {
     "@babel/core": "workspace:*",
-    "@babel/helper-plugin-test-runner": "workspace:*"
+    "@babel/helper-plugin-test-runner": "workspace:*",
+    "@babel/traverse": "workspace:*",
+    "@babel/types": "workspace:*"
   },
   "homepage": "https://babel.dev/docs/en/next/babel-plugin-transform-typescript"
 }
diff --git a/packages/babel-plugin-transform-typescript/src/enum.js b/packages/babel-plugin-transform-typescript/src/enum.ts
similarity index 95%
rename from packages/babel-plugin-transform-typescript/src/enum.js
rename to packages/babel-plugin-transform-typescript/src/enum.ts
index 808f2fcf49..156ccda524 100644
--- a/packages/babel-plugin-transform-typescript/src/enum.js
+++ b/packages/babel-plugin-transform-typescript/src/enum.ts
@@ -1,5 +1,7 @@
 import assert from "assert";
 import { template } from "@babel/core";
+import type * as t from "@babel/types";
+import type { NodePath } from "@babel/traverse";
 
 export default function transpileEnum(path, t) {
   const { node } = path;
@@ -35,7 +37,7 @@ export default function transpileEnum(path, t) {
       throw new Error(`Unexpected enum parent '${path.parent.type}`);
   }
 
-  function seen(parentPath: Path<Node>) {
+  function seen(parentPath: NodePath<t.Node>) {
     if (parentPath.isExportDeclaration()) {
       return seen(parentPath.parentPath);
     }
@@ -49,7 +51,7 @@ export default function transpileEnum(path, t) {
   }
 }
 
-function makeVar(id, t, kind): VariableDeclaration {
+function makeVar(id, t, kind) {
   return t.variableDeclaration(kind, [t.variableDeclarator(id)]);
 }
 
@@ -99,7 +101,9 @@ function enumFill(path, t, id) {
  *     Z = X | Y,
  *   }
  */
-type PreviousEnumMembers = { [name: string]: number | string };
+type PreviousEnumMembers = {
+  [name: string]: number | string;
+};
 
 function translateEnumValues(path, t) {
   const seen: PreviousEnumMembers = Object.create(null);
@@ -108,7 +112,7 @@ function translateEnumValues(path, t) {
   return path.node.members.map(member => {
     const name = t.isIdentifier(member.id) ? member.id.name : member.id.value;
     const initializer = member.initializer;
-    let value: Expression;
+    let value: t.Expression;
     if (initializer) {
       const constValue = evaluate(initializer, seen);
       if (constValue !== undefined) {
diff --git a/packages/babel-plugin-transform-typescript/src/index.js b/packages/babel-plugin-transform-typescript/src/index.ts
similarity index 98%
rename from packages/babel-plugin-transform-typescript/src/index.js
rename to packages/babel-plugin-transform-typescript/src/index.ts
index 4073d96c59..aec840965b 100644
--- a/packages/babel-plugin-transform-typescript/src/index.js
+++ b/packages/babel-plugin-transform-typescript/src/index.ts
@@ -5,6 +5,7 @@ import { injectInitialization } from "@babel/helper-create-class-features-plugin
 
 import transpileEnum from "./enum";
 import transpileNamespace from "./namespace";
+import type { NodePath } from "@babel/traverse";
 
 function isInType(path) {
   switch (path.parent.type) {
@@ -184,7 +185,7 @@ export default declare((api, opts) => {
         }
 
         if (file.ast.comments) {
-          for (const comment of (file.ast.comments: Array<Object>)) {
+          for (const comment of file.ast.comments) {
             const jsxMatches = JSX_PRAGMA_REGEX.exec(comment.value);
             if (jsxMatches) {
               if (jsxMatches[1]) {
@@ -209,7 +210,7 @@ export default declare((api, opts) => {
 
         // remove type imports
         for (let stmt of path.get("body")) {
-          if (t.isImportDeclaration(stmt)) {
+          if (stmt.isImportDeclaration()) {
             if (stmt.node.importKind === "type") {
               stmt.remove();
               continue;
@@ -225,7 +226,7 @@ export default declare((api, opts) => {
               }
 
               let allElided = true;
-              const importsToRemove: Path<Node>[] = [];
+              const importsToRemove: NodePath<t.Node>[] = [];
 
               for (const specifier of stmt.node.specifiers) {
                 const binding = stmt.scope.getBinding(specifier.local.name);
@@ -373,13 +374,13 @@ export default declare((api, opts) => {
             if (child.node.kind === "constructor") {
               classMemberVisitors.constructor(child, path);
             } else {
-              classMemberVisitors.method(child, path);
+              classMemberVisitors.method(child);
             }
           } else if (
             child.isClassProperty() ||
             child.isClassPrivateProperty()
           ) {
-            classMemberVisitors.field(child, path);
+            classMemberVisitors.field(child);
           }
         });
       },
diff --git a/packages/babel-plugin-transform-typescript/src/namespace.js b/packages/babel-plugin-transform-typescript/src/namespace.ts
similarity index 96%
rename from packages/babel-plugin-transform-typescript/src/namespace.js
rename to packages/babel-plugin-transform-typescript/src/namespace.ts
index 664326f462..84ea984864 100644
--- a/packages/babel-plugin-transform-typescript/src/namespace.js
+++ b/packages/babel-plugin-transform-typescript/src/namespace.ts
@@ -67,10 +67,14 @@ function handleVariableDeclaration(
     );
   }
   const { declarations } = node;
-  if (declarations.every(declarator => t.isIdentifier(declarator.id))) {
+  if (
+    declarations.every((declarator): declarator is t.VariableDeclarator & {
+      id: t.Identifier;
+    } => t.isIdentifier(declarator.id))
+  ) {
     // `export const a = 1` transforms to `const a = N.a = 1`, the output
     // is smaller than `const a = 1; N.a = a`;
-    for (const declarator of node.declarations) {
+    for (const declarator of declarations) {
       declarator.init = t.assignmentExpression(
         "=",
         getMemberExpression(t, name, declarator.id.name),
@@ -97,7 +101,7 @@ function handleVariableDeclaration(
   return [node, t.expressionStatement(t.sequenceExpression(assignments))];
 }
 
-function handleNested(path, t, node, parentExport) {
+function handleNested(path, t, node, parentExport?) {
   const names = new Set();
   const realName = node.id;
   const name = path.scope.generateUid(realName.name);
diff --git a/tsconfig.json b/tsconfig.json
index 98d6c1a107..2fc9a72dbc 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -27,6 +27,7 @@
     "./packages/babel-plugin-proposal-async-do-expressions/src/**/*.ts",
     "./packages/babel-plugin-syntax-async-do-expressions/src/**/*.ts",
     "./packages/babel-plugin-transform-react-jsx/src/**/*.ts",
+    "./packages/babel-plugin-transform-typescript/src/**/*.ts",
     "./packages/babel-template/src/**/*.ts",
     "./packages/babel-traverse/src/**/*.ts",
     "./packages/babel-types/src/**/*.ts"
@@ -108,6 +109,9 @@
       "@babel/plugin-transform-react-jsx": [
         "./packages/babel-plugin-transform-react-jsx/src"
       ],
+      "@babel/plugin-transform-typescript": [
+        "./packages/babel-plugin-transform-typescript/src"
+      ],
       "@babel/template": [
         "./packages/babel-template/src"
       ],
diff --git a/yarn.lock b/yarn.lock
index 506cefb067..cbb92c2784 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3012,6 +3012,8 @@ __metadata:
     "@babel/helper-plugin-test-runner": "workspace:*"
     "@babel/helper-plugin-utils": "workspace:^7.13.0"
     "@babel/plugin-syntax-typescript": "workspace:^7.12.13"
+    "@babel/traverse": "workspace:*"
+    "@babel/types": "workspace:*"
   peerDependencies:
     "@babel/core": ^7.0.0-0
   languageName: unknown