How to Completely Disable ‘Windows Defender Antivirus’ System-Wide in Windows 11

Windows Defender is the built-in antivirus and anti-malware solution integrated directly into the core of Windows 11. For the vast majority of users, it provides excellent, unobtrusive protection against zero-day threats and malicious downloads. However, for specialized use cases—such as running isolated benchmark tests, deploying a secondary third-party enterprise security suite that conflicts with Defender, or managing heavily resource-constrained offline kiosks—the constant background scanning and real-time protection heuristics can cause unacceptable CPU overhead and disk thrashing.

This guide explains how to completely and permanently disable the Windows Defender Antivirus engine system-wide in Windows 11 using the Group Policy Editor.

Important Security Warning

Proceed with extreme caution. Completely disabling Windows Defender leaves your system entirely vulnerable to viruses, ransomware, and spyware unless you immediately install a capable third-party antivirus replacement. Do not perform these steps on a daily-driver machine connected to the public internet without an alternative security plan in place.

Disable Defender via Group Policy (Windows 11 Pro/Enterprise)

If you are running Windows 11 Pro, Enterprise, or Education, the cleanest way to disable the antivirus engine is through the Local Group Policy Editor.

1. Before modifying the policy, you must first disable “Tamper Protection.” Open the Windows Security app (search for it in the Start Menu).
2. Click on Virus & threat protection.
3. Under the “Virus & threat protection settings” heading, click Manage settings.
4. Scroll down to find Tamper Protection and toggle the switch to Off. (If you do not do this first, Windows will silently ignore your Group Policy changes).
5. Close the Windows Security app.
6. Press Windows Key + R to open the Run dialogue box.
7. Type gpedit.msc and press Enter to launch the Local Group Policy Editor.
8. In the left-hand navigation pane, drill down to the following path:
   Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus
9. In the right-hand pane, look for a policy named Turn off Microsoft Defender Antivirus.
10. Double-click this policy to open its configuration window.
11. Change the radial button setting from “Not Configured” to Enabled. (Counter-intuitively, you must “Enable” the policy to “Turn off” the antivirus).
12. Click Apply, then click OK.
13. Restart your computer.

Upon reboot, the core MsMpEng.exe executable will no longer load into memory, and all real-time scanning will be permanently halted.