diff --git a/packages/vite/src/node/plugins/define.ts b/packages/vite/src/node/plugins/define.ts
index ca0f446cc1f58e..6edb1bd8858a11 100644
--- a/packages/vite/src/node/plugins/define.ts
+++ b/packages/vite/src/node/plugins/define.ts
@@ -10,15 +10,23 @@ const isNonJsRequest = (request: string): boolean => nonJsRe.test(request)
 
 export function definePlugin(config: ResolvedConfig): Plugin {
   const isBuild = config.command === 'build'
-
-  const processNodeEnv: Record<string, string> = {
-    'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || config.mode),
-    'global.process.env.NODE_ENV': JSON.stringify(
-      process.env.NODE_ENV || config.mode
-    ),
-    'globalThis.process.env.NODE_ENV': JSON.stringify(
-      process.env.NODE_ENV || config.mode
-    )
+  const isBuildLib = isBuild && config.build.lib
+
+  // ignore replace process.env in lib build
+  const processEnv: Record<string, string> = {}
+  const processNodeEnv: Record<string, string> = {}
+  if (!isBuildLib) {
+    const nodeEnv = process.env.NODE_ENV || config.mode
+    Object.assign(processEnv, {
+      'process.env.': `({}).`,
+      'global.process.env.': `({}).`,
+      'globalThis.process.env.': `({}).`
+    })
+    Object.assign(processNodeEnv, {
+      'process.env.NODE_ENV': JSON.stringify(nodeEnv),
+      'global.process.env.NODE_ENV': JSON.stringify(nodeEnv),
+      'globalThis.process.env.NODE_ENV': JSON.stringify(nodeEnv)
+    })
   }
 
   const userDefine: Record<string, string> = {}
@@ -27,7 +35,8 @@ export function definePlugin(config: ResolvedConfig): Plugin {
     userDefine[key] = typeof val === 'string' ? val : JSON.stringify(val)
   }
 
-  // during dev, import.meta properties are handled by importAnalysis plugin
+  // during dev, import.meta properties are handled by importAnalysis plugin.
+  // ignore replace import.meta.env in lib build
   const importMetaKeys: Record<string, string> = {}
   if (isBuild) {
     const env: Record<string, any> = {
@@ -47,22 +56,13 @@ export function definePlugin(config: ResolvedConfig): Plugin {
   function generatePattern(
     ssr: boolean
   ): [Record<string, string | undefined>, RegExp | null] {
-    const processEnv: Record<string, string> = {}
-    const isNeedProcessEnv = !ssr || config.ssr?.target === 'webworker'
-
-    if (isNeedProcessEnv) {
-      Object.assign(processEnv, {
-        'process.env.': `({}).`,
-        'global.process.env.': `({}).`,
-        'globalThis.process.env.': `({}).`
-      })
-    }
+    const replaceProcessEnv = !ssr || config.ssr?.target === 'webworker'
 
     const replacements: Record<string, string> = {
-      ...(isNeedProcessEnv ? processNodeEnv : {}),
+      ...(replaceProcessEnv ? processNodeEnv : {}),
       ...userDefine,
       ...importMetaKeys,
-      ...processEnv
+      ...(replaceProcessEnv ? processEnv : {})
     }
 
     const replacementsKeys = Object.keys(replacements)
diff --git a/playground/lib/__tests__/lib.spec.ts b/playground/lib/__tests__/lib.spec.ts
index 32c6edba1bdeb9..9046097f7e8375 100644
--- a/playground/lib/__tests__/lib.spec.ts
+++ b/playground/lib/__tests__/lib.spec.ts
@@ -1,11 +1,9 @@
-import path from 'path'
-import fs from 'fs'
 import {
   isBuild,
   isServe,
   page,
+  readFile,
   serverLogs,
-  testDir,
   untilUpdated
 } from '~utils'
 
@@ -16,20 +14,14 @@ describe.runIf(isBuild)('build', () => {
 
   test('umd', async () => {
     expect(await page.textContent('.umd')).toBe('It works')
-    const code = fs.readFileSync(
-      path.join(testDir, 'dist/my-lib-custom-filename.umd.js'),
-      'utf-8'
-    )
+    const code = readFile('dist/my-lib-custom-filename.umd.js')
     // esbuild helpers are injected inside of the UMD wrapper
     expect(code).toMatch(/^\(function\(/)
   })
 
   test('iife', async () => {
     expect(await page.textContent('.iife')).toBe('It works')
-    const code = fs.readFileSync(
-      path.join(testDir, 'dist/my-lib-custom-filename.iife.js'),
-      'utf-8'
-    )
+    const code = readFile('dist/my-lib-custom-filename.iife.js')
     // esbuild helpers are injected inside of the IIFE wrapper
     expect(code).toMatch(/^const MyLib=function\(\){"use strict";/)
   })
@@ -39,10 +31,7 @@ describe.runIf(isBuild)('build', () => {
       () => page.textContent('.dynamic-import-message'),
       'hello vite'
     )
-    const code = fs.readFileSync(
-      path.join(testDir, 'dist/lib/dynamic-import-message.es.mjs'),
-      'utf-8'
-    )
+    const code = readFile('dist/lib/dynamic-import-message.es.mjs')
     expect(code).not.toMatch('__vitePreload')
 
     // Test that library chunks are hashed
@@ -55,6 +44,15 @@ describe.runIf(isBuild)('build', () => {
       expect(log).not.toMatch('All "@import" rules must come first')
     })
   })
+
+  test('preserve process.env', () => {
+    const es = readFile('dist/my-lib-custom-filename.mjs')
+    const iife = readFile('dist/my-lib-custom-filename.iife.js')
+    const umd = readFile('dist/my-lib-custom-filename.umd.js')
+    expect(es).toMatch('process.env.NODE_ENV')
+    expect(iife).toMatch('process.env.NODE_ENV')
+    expect(umd).toMatch('process.env.NODE_ENV')
+  })
 })
 
 test.runIf(isServe)('dev', async () => {
diff --git a/playground/lib/index.dist.html b/playground/lib/index.dist.html
index 02362a9c111e5e..99f08c73396fea 100644
--- a/playground/lib/index.dist.html
+++ b/playground/lib/index.dist.html
@@ -4,6 +4,15 @@
 <div class="iife"></div>
 <div class="dynamic-import-message"></div>
 
+<script>
+  // shim test preserve process.env.NODE_ENV
+  globalThis.process = {
+    env: {
+      NODE_ENV: 'production'
+    }
+  }
+</script>
+
 <script type="module">
   import myLib from './my-lib-custom-filename.mjs'
 
diff --git a/playground/lib/src/main.js b/playground/lib/src/main.js
index cb2fb3b842dc4f..ca7adf0a873ae6 100644
--- a/playground/lib/src/main.js
+++ b/playground/lib/src/main.js
@@ -3,4 +3,7 @@ export default function myLib(sel) {
   console.log({ ...'foo' })
 
   document.querySelector(sel).textContent = 'It works'
+
+  // Env vars should not be replaced
+  console.log(process.env.NODE_ENV)
 }