diff --git a/src/cjs/api/register.ts b/src/cjs/api/register.ts
index 8c08646b4..e4d30e7d7 100644
--- a/src/cjs/api/register.ts
+++ b/src/cjs/api/register.ts
@@ -4,6 +4,7 @@ import { fileURLToPath } from 'node:url';
 import { loadTsconfig } from '../../utils/tsconfig.js';
 import type { RequiredProperty } from '../../types.js';
 import { urlSearchParamsStringify } from '../../utils/url-search-params-stringify.js';
+import { fileUrlPrefix } from '../../utils/path-utils.js';
 import type { LoaderState } from './types.js';
 import { createExtensions } from './module-extensions.js';
 import { createResolveFilename } from './module-resolve-filename.js';
@@ -22,7 +23,7 @@ const resolveContext = (
 	}
 
 	if (
-		(typeof fromFile === 'string' && fromFile.startsWith('file://'))
+		(typeof fromFile === 'string' && fromFile.startsWith(fileUrlPrefix))
 		|| fromFile instanceof URL
 	) {
 		fromFile = fileURLToPath(fromFile);
diff --git a/src/esm/api/scoped-import.ts b/src/esm/api/scoped-import.ts
index efe205cf5..6482c9f77 100644
--- a/src/esm/api/scoped-import.ts
+++ b/src/esm/api/scoped-import.ts
@@ -1,44 +1,33 @@
 import { pathToFileURL } from 'node:url';
-
-const resolveSpecifier = (
-	specifier: string,
-	fromFile: string,
-	namespace: string,
-) => {
-	const base = (
-		fromFile.startsWith('file://')
-			? fromFile
-			: pathToFileURL(fromFile)
-	);
-	const resolvedUrl = new URL(specifier, base);
-
-	/**
-	 * A namespace query is added so we get our own module cache
-	 *
-	 * I considered using an import attribute for this, but it doesn't seem to
-	 * make the request unique so it gets cached.
-	 */
-	resolvedUrl.searchParams.set('tsx-namespace', namespace);
-
-	return resolvedUrl.toString();
-};
+import type { TsxRequest } from '../types.js';
+import { fileUrlPrefix } from '../../utils/path-utils.js';
 
 export type ScopedImport = (
 	specifier: string,
-	parentURL: string,
+	parent: string,
 ) => Promise<any>; // eslint-disable-line @typescript-eslint/no-explicit-any
 
 export const createScopedImport = (
 	namespace: string,
 ): ScopedImport => (
 	specifier,
-	parentURL,
+	parent,
 ) => {
-	if (!parentURL) {
+	if (!parent) {
 		throw new Error('The current file path (import.meta.url) must be provided in the second argument of tsImport()');
 	}
 
+	const parentURL = (
+		parent.startsWith(fileUrlPrefix)
+			? parent
+			: pathToFileURL(parent).toString()
+	);
+
 	return import(
-		resolveSpecifier(specifier, parentURL, namespace)
+		`tsx://${JSON.stringify({
+			specifier,
+			parentURL,
+			namespace,
+		} satisfies TsxRequest)}`
 	);
 };
diff --git a/src/esm/api/ts-import.ts b/src/esm/api/ts-import.ts
index 02268f4c7..255cd02bf 100644
--- a/src/esm/api/ts-import.ts
+++ b/src/esm/api/ts-import.ts
@@ -1,4 +1,6 @@
 import { register as cjsRegister } from '../../cjs/api/index.js';
+import { isFeatureSupported, esmLoadReadFile } from '../../utils/node-features.js';
+import { isBarePackageNamePattern, cjsExtensionPattern } from '../../utils/path-utils.js';
 import { register, type TsconfigOptions } from './register.js';
 
 type Options = {
@@ -6,6 +8,7 @@ type Options = {
 	onImport?: (url: string) => void;
 	tsconfig?: TsconfigOptions;
 };
+
 const tsImport = (
 	specifier: string,
 	options: string | Options,
@@ -22,10 +25,26 @@ const tsImport = (
 	const namespace = Date.now().toString();
 
 	// Keep registered for hanging require() calls
-	cjsRegister({
+	const cjs = cjsRegister({
 		namespace,
 	});
 
+	/**
+	 * In Node v18, the loader doesn't support reading the CommonJS from
+	 * a data URL, so it can't actually relay the namespace. This is a workaround
+	 * to preemptively determine whether the file is a CommonJS file, and shortcut
+	 * to using the CommonJS loader instead of going through the ESM loader first
+	 */
+	if (
+		!isFeatureSupported(esmLoadReadFile)
+		&& (
+			!isBarePackageNamePattern.test(specifier)
+			&& cjsExtensionPattern.test(specifier)
+		)
+	) {
+		return Promise.resolve(cjs.require(specifier, parentURL));
+	}
+
 	/**
 	 * We don't want to unregister this after load since there can be child import() calls
 	 * that need TS support
diff --git a/src/esm/hook/load.ts b/src/esm/hook/load.ts
index de7b46ccc..0df3a6044 100644
--- a/src/esm/hook/load.ts
+++ b/src/esm/hook/load.ts
@@ -9,7 +9,7 @@ import { isFeatureSupported, importAttributes, esmLoadReadFile } from '../../uti
 import { parent } from '../../utils/ipc/client.js';
 import type { Message } from '../types.js';
 import { fileMatcher } from '../../utils/tsconfig.js';
-import { isJsonPattern, tsExtensionsPattern } from '../../utils/path-utils.js';
+import { isJsonPattern, tsExtensionsPattern, fileUrlPrefix } from '../../utils/path-utils.js';
 import { isESM } from '../../utils/es-module-lexer.js';
 import { getNamespace } from './utils.js';
 import { data } from './initialize.js';
@@ -63,7 +63,7 @@ export const load: LoadHook = async (
 	}
 
 	const loaded = await nextLoad(url, context);
-	const filePath = url.startsWith('file://') ? fileURLToPath(url) : url;
+	const filePath = url.startsWith(fileUrlPrefix) ? fileURLToPath(url) : url;
 
 	if (
 		loaded.format === 'commonjs'
diff --git a/src/esm/hook/resolve.ts b/src/esm/hook/resolve.ts
index 0bf02f4f2..2470ce3ff 100644
--- a/src/esm/hook/resolve.ts
+++ b/src/esm/hook/resolve.ts
@@ -16,6 +16,7 @@ import {
 	isDirectoryPattern,
 	isBarePackageNamePattern,
 } from '../../utils/path-utils.js';
+import type { TsxRequest } from '../types.js';
 import {
 	getFormatFromFileUrl,
 	namespaceQuery,
@@ -205,6 +206,8 @@ const resolveTsPaths: ResolveHook = async (
 	return resolveDirectory(specifier, context, nextResolve);
 };
 
+const tsxProtocol = 'tsx://';
+
 export const resolve: ResolveHook = async (
 	specifier,
 	context,
@@ -214,13 +217,33 @@ export const resolve: ResolveHook = async (
 		return nextResolve(specifier, context);
 	}
 
-	const requestNamespace = getNamespace(specifier) ?? (
+	let requestNamespace = getNamespace(specifier) ?? (
 		// Inherit namespace from parent
 		context.parentURL && getNamespace(context.parentURL)
 	);
 
-	if (data.namespace && data.namespace !== requestNamespace) {
-		return nextResolve(specifier, context);
+	if (data.namespace) {
+		let tsImportRequest: TsxRequest | undefined;
+
+		// Initial request from tsImport()
+		if (specifier.startsWith(tsxProtocol)) {
+			try {
+				tsImportRequest = JSON.parse(specifier.slice(tsxProtocol.length));
+			} catch {}
+
+			if (tsImportRequest?.namespace) {
+				requestNamespace = tsImportRequest.namespace;
+			}
+		}
+
+		if (data.namespace !== requestNamespace) {
+			return nextResolve(specifier, context);
+		}
+
+		if (tsImportRequest) {
+			specifier = tsImportRequest.specifier;
+			context.parentURL = tsImportRequest.parentURL;
+		}
 	}
 
 	const [cleanSpecifier, query] = specifier.split('?');
diff --git a/src/esm/types.ts b/src/esm/types.ts
index ee1372704..e97ee7b0c 100644
--- a/src/esm/types.ts
+++ b/src/esm/types.ts
@@ -4,3 +4,9 @@ export type Message = {
 	type: 'load';
 	url: string;
 };
+
+export type TsxRequest = {
+	namespace: string;
+	parentURL: string;
+	specifier: string;
+};
diff --git a/src/utils/path-utils.ts b/src/utils/path-utils.ts
index 055c5e130..373c8dfd1 100644
--- a/src/utils/path-utils.ts
+++ b/src/utils/path-utils.ts
@@ -48,6 +48,8 @@ export const fileUrlPrefix = 'file://';
 
 export const tsExtensionsPattern = /\.([cm]?ts|[tj]sx)($|\?)/;
 
+export const cjsExtensionPattern = /[/\\].+\.(?:cts|cjs)(?:$|\?)/;
+
 export const isJsonPattern = /\.json($|\?)/;
 
 export const isDirectoryPattern = /\/(?:$|\?)/;
diff --git a/tests/specs/api.ts b/tests/specs/api.ts
index 23b000a5e..8a6d0d17a 100644
--- a/tests/specs/api.ts
+++ b/tests/specs/api.ts
@@ -50,13 +50,23 @@ const tsFiles = {
 	'bar.ts': 'export type A = 1; export { bar } from "pkg"',
 	'async.ts': 'export default "async"',
 	'json.json': JSON.stringify({ json: 'json' }),
-	'node_modules/pkg': {
-		'package.json': createPackageJson({
-			name: 'pkg',
-			type: 'module',
-			exports: './pkg.js',
-		}),
-		'pkg.js': 'import "node:process"; export const bar = "bar";',
+	node_modules: {
+		pkg: {
+			'package.json': createPackageJson({
+				name: 'pkg',
+				type: 'module',
+				exports: './pkg.js',
+			}),
+			'pkg.js': 'import "node:process"; export const bar = "bar";',
+		},
+		'@a/b.cjs': {
+			'package.json': createPackageJson({
+				name: '@a/b.cjs',
+				type: 'module',
+				exports: './pkg.js',
+			}),
+			'pkg.js': 'import "node:process"; export const bar = "bar";',
+		},
 	},
 	'tsconfig.json': createTsconfig({
 		compilerOptions: {
@@ -662,8 +672,13 @@ export default testSuite(({ describe }, node: NodeApis) => {
 							// Loads cts vis CJS namespace even if there are no exports
 							await tsImport('./cjs/exports-no.cts', import.meta.url).catch((error) => console.log(error.constructor.name))
 
-							const cjsExport = await tsImport('./cjs/exports-yes.cts', import.meta.url).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
-							console.log(cjsExport);
+							const cts = await tsImport('./cjs/exports-yes.cts', import.meta.url).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
+							console.log(cts);
+
+							const cjs = await tsImport('./cjs/reexport.cjs?query', import.meta.url).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
+							console.log(cjs);
+
+							await tsImport('@a/b.cjs', import.meta.url);
 
 							const { message: message2 } = await tsImport('./file.ts?with-query', import.meta.url);
 							console.log(message2);
@@ -682,11 +697,15 @@ export default testSuite(({ describe }, node: NodeApis) => {
 							nodeOptions: [],
 						});
 
-						if (node.supports.cjsInterop) {
-							expect(stdout).toMatch(/Fails as expected 1\nfoo bar json file\.ts\?tsx-namespace=\d+\ncts loaded\ncjsReexport esm syntax\nfoo bar json file\.ts\?with-query=&tsx-namespace=\d+\nFails as expected 2/);
-						} else {
-							expect(stdout).toMatch(/Fails as expected 1\nfoo bar json file\.ts\?tsx-namespace=\d+\nSyntaxError\nSyntaxError\nfoo bar json file\.ts\?with-query=&tsx-namespace=\d+\nFails as expected 2/);
-						}
+						expect(stdout).toMatch(new RegExp([
+							'Fails as expected 1',
+							String.raw`foo bar json file\.ts\?tsx-namespace=\d+`,
+							'cts loaded',
+							'cjsReexport esm syntax',
+							'cjsReexport esm syntax',
+							String.raw`foo bar json file\.ts\?with-query&tsx-namespace=\d+`,
+							'Fails as expected 2',
+						].join(String.raw`\n`)));
 					});
 
 					test('commonjs', async () => {
@@ -706,12 +725,14 @@ export default testSuite(({ describe }, node: NodeApis) => {
 								const { message: message2 } = await tsImport('./file.ts?with-query', __filename);
 								console.log(message2);
 
-								const cts = await tsImport('./cjs/exports-yes.cts', __filename).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
+								const cts = await tsImport('./cjs/exports-yes.cts?query', __filename).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
 								console.log(cts);
 
-								const cjs = await tsImport('./cjs/reexport.cjs', __filename).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
+								const cjs = await tsImport('./cjs/reexport.cjs?query', __filename).then(({ cjsReexport, esmSyntax }) => \`\${cjsReexport} \${esmSyntax}\`, err => err.constructor.name);
 								console.log(cjs);
 
+								await tsImport('@a/b.cjs', __filename);
+
 								// Global not polluted
 								await import('./file.ts?nocache').catch((error) => {
 									console.log('Fails as expected 2');
@@ -725,25 +746,15 @@ export default testSuite(({ describe }, node: NodeApis) => {
 							nodePath: node.path,
 							nodeOptions: [],
 						});
-						if (node.supports.cjsInterop) {
-							expect(stdout).toMatch(new RegExp(
-								`${String.raw`Fails as expected 1\n`
-								+ String.raw`foo bar json file\.ts\?tsx-namespace=\d+\n`
-								+ String.raw`foo bar json file\.ts\?with-query=&tsx-namespace=\d+\n`
-								+ String.raw`cjsReexport esm syntax\n`
-								+ String.raw`cjsReexport esm syntax\n`
-								}Fails as expected 2`,
-							));
-						} else {
-							expect(stdout).toMatch(new RegExp(
-								`${String.raw`Fails as expected 1\n`
-								+ String.raw`foo bar json file\.ts\?tsx-namespace=\d+\n`
-								+ String.raw`foo bar json file\.ts\?with-query=&tsx-namespace=\d+\n`
-								+ String.raw`SyntaxError\n`
-								+ String.raw`Error\n`
-								}Fails as expected 2`,
-							));
-						}
+
+						expect(stdout).toMatch(new RegExp([
+							'Fails as expected 1',
+							String.raw`foo bar json file\.ts\?tsx-namespace=\d+`,
+							String.raw`foo bar json file\.ts\?with-query&tsx-namespace=\d+`,
+							'cjsReexport esm syntax',
+							'cjsReexport esm syntax',
+							'Fails as expected 2',
+						].join(String.raw`\n`)));
 					});
 
 					test('mts from commonjs', async () => {