diff --git a/packages/core/package.json b/packages/core/package.json
index cc9407fa0c..3dbf790cf6 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -74,7 +74,6 @@
     "cors": "^2.8.5",
     "css-loader": "7.1.2",
     "deepmerge": "^4.3.1",
-    "dotenv": "16.5.0",
     "dotenv-expand": "12.0.2",
     "html-rspack-plugin": "6.1.2",
     "http-proxy-middleware": "^2.0.9",
diff --git a/packages/core/src/loadEnv.ts b/packages/core/src/loadEnv.ts
index 736fe7f766..f4c0ab279a 100644
--- a/packages/core/src/loadEnv.ts
+++ b/packages/core/src/loadEnv.ts
@@ -1,10 +1,60 @@
 import fs from 'node:fs';
 import { join } from 'node:path';
-import { parse } from 'dotenv';
 import { expand } from 'dotenv-expand';
 import { color, getNodeEnv, isFileSync } from './helpers';
 import { logger } from './logger';
 
+const DOTENV_LINE =
+  /(?:^|^)\s*(?:export\s+)?([\w.-]+)(?:\s*=\s*?|:\s+?)(\s*'(?:\\'|[^'])*'|\s*"(?:\\"|[^"])*"|\s*`(?:\\`|[^`])*`|[^#\r\n]+)?\s*(?:#.*)?(?:$|$)/gm;
+
+/**
+ * This method is modified based on source found in
+ * https://github.com/motdotla/dotenv/blob/v16.5.0/lib/main.js#L9-L48
+ *
+ * Copyright (c) 2015, Scott Motte
+ *
+ * We copied this method because Rsbuild only uses the `parse` method
+ * in dotenv and most of the other code is redundant.
+ */
+function parse(src: Buffer) {
+  const obj: Record<string, string> = {};
+
+  // Convert buffer to string
+  let lines = src.toString();
+
+  // Convert line breaks to same format
+  lines = lines.replace(/\r\n?/gm, '\n');
+
+  let match: RegExpExecArray | null;
+  // biome-ignore lint/suspicious/noAssignInExpressions: allowed
+  while ((match = DOTENV_LINE.exec(lines)) != null) {
+    const key = match[1];
+
+    // Default undefined or null to empty string
+    let value = match[2] || '';
+
+    // Remove whitespace
+    value = value.trim();
+
+    // Check if double quoted
+    const maybeQuote = value[0];
+
+    // Remove surrounding quotes
+    value = value.replace(/^(['"`])([\s\S]*)\1$/gm, '$2');
+
+    // Expand newlines if double quoted
+    if (maybeQuote === '"') {
+      value = value.replace(/\\n/g, '\n');
+      value = value.replace(/\\r/g, '\r');
+    }
+
+    // Add to object
+    obj[key] = value;
+  }
+
+  return obj;
+}
+
 export type LoadEnvOptions = {
   /**
    * The root path to load the env file
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 9f7fd35a1c..cfb5019249 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -657,9 +657,6 @@ importers:
       deepmerge:
         specifier: ^4.3.1
         version: 4.3.1
-      dotenv:
-        specifier: 16.5.0
-        version: 16.5.0
       dotenv-expand:
         specifier: 12.0.2
         version: 12.0.2