How To Turn On Windows Defender In Windows 11: A Step-by-Step Guide

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5 min. read

Published on October 15, 2025

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Windows Defender, now known as Microsoft Defender Antivirus, is your first line of defense against malware and other threats in Windows 11. It runs quietly in the background, providing real-time protection without the need for additional software in many cases. Knowing how to ensure it’s active is crucial for maintaining a secure computing environment.

This guide will walk you through the simple steps to turn on and configure Microsoft Defender Antivirus in Windows 11, ensuring your system is protected against the latest threats. We’ll cover various methods and settings so you can be confident your computer is safe.

How Do I Enable Microsoft Defender Antivirus in Windows 11?

Checking if Windows Defender is Already Enabled

Before diving into enabling Defender, it’s a good idea to check if it’s already running.

Open the Settings app. You can do this by pressing the Windows key + I.
Click on Privacy & security in the left-hand menu.
Select Windows Security.
Click on Virus & threat protection. If Defender is active, you’ll see a green checkmark and a message like “No actions needed.”

Enabling Windows Defender Through the Windows Security App

If Defender is disabled, follow these steps to enable it:

Open the Windows Security app (as described above).
Click on Virus & threat protection.
Look for a message indicating that protection is off. Click the Turn on button, if available.
If you don’t see a “Turn on” button but instead see options to manage other antivirus programs, uninstall those programs. Windows Defender often disables itself when it detects another antivirus solution.
Restart your computer after uninstalling any conflicting antivirus software. This will allow Windows Defender to take over.

Enabling Windows Defender Through Group Policy Editor (for advanced users)

This method is useful if you suspect a policy is preventing Defender from running.

Press the Windows key + R to open the Run dialog box.
Type gpedit.msc and press Enter. This opens the Local Group Policy Editor. (Note: This is only available on Windows 11 Pro, Enterprise, and Education editions.)
Navigate to Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus.
In the right pane, find the setting Turn off Microsoft Defender Antivirus.
Double-click on Turn off Microsoft Defender Antivirus.
Select Disabled or Not Configured.
Click Apply and then OK.
Restart your computer.

Enabling Windows Defender Through Registry Editor (for advanced users)

If Group Policy Editor isn’t available, you can use the Registry Editor.

Press the Windows key + R to open the Run dialog box.
Type regedit and press Enter. This opens the Registry Editor.
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender.
In the right pane, look for a DWORD value named DisableAntiSpyware.
If it exists, double-click on DisableAntiSpyware and set its value to 0. If it doesn’t exist, right-click in the right pane, select New > DWORD (32-bit) Value, and name it DisableAntiSpyware. Then, set its value to 0.
Restart your computer.

Tips for Keeping Windows Defender Active

Regularly update Windows to ensure you have the latest security definitions.
Avoid installing multiple antivirus programs simultaneously, as they can conflict with each other.
Periodically check the Windows Security app to confirm that Defender is running and up-to-date.
Be cautious when opening email attachments or clicking on links from unknown sources.

Windows Defender: Key Differences Between Windows 10 and 11

Feature	Windows 10	Windows 11
Interface	Integrated within the Windows Security Center, providing a centralized view of security settings.	Same as Windows 10, but with a visually refreshed interface and improved navigation.
Ransomware Protection	Offers controlled folder access to protect important files from ransomware attacks.	Enhanced ransomware protection features, including integration with OneDrive for file recovery and improved detection algorithms.
Cloud-Based Protection	Utilizes cloud-based threat intelligence to quickly identify and block emerging threats.	Continued cloud-based protection with enhanced machine learning capabilities for more accurate and proactive threat detection.
Performance Impact	Generally lightweight, but can occasionally cause performance slowdowns during scans.	Optimized for performance, with reduced impact on system resources during scans and real-time protection.

Ensuring Your System’s Security

Keeping Microsoft Defender Antivirus enabled is a simple yet effective way to protect your Windows 11 computer from online threats. By following these steps, you can ensure that your system remains secure and protected against malware and other malicious software.

FAQ

How do I know if Windows Defender is working properly? Open the Windows Security app and check for a green checkmark next to “Virus & threat protection.” This indicates that Defender is active and up-to-date.

Can I use another antivirus program alongside Windows Defender? It’s generally not recommended to run multiple antivirus programs simultaneously, as they can conflict with each other and cause performance issues.

How often should I update Windows Defender? Windows Defender automatically updates its virus definitions regularly. However, you can manually check for updates in the Windows Security app under “Virus & threat protection.”

What should I do if Windows Defender detects a threat? Follow the on-screen instructions provided by Windows Defender to remove or quarantine the threat.

Is Windows Defender enough protection for my computer? For most users, Windows Defender provides adequate protection. However, if you engage in high-risk activities online, you may consider using a third-party antivirus solution for added security.