Windows

How to Activate Microsoft Defender in Windows 11

Richard
Written by
Richard
Jul 9, 2021 Updated Apr 14, 2026 1 min read

Microsoft Defender is the built-in security tool for Windows 11. It keeps your computer safe from viruses and hackers. If you do not have another security program, you should keep this turned on.

Why: You need it to block harmful software and unauthorized access to your files.

What happens when done: Your computer will be actively monitored for threats and protected by a firewall.

How to Enable Microsoft Defender

You can manage your security settings through the main Windows Settings menu. %%LNK0%%

1. Open the Settings app by pressing Windows key + I on your keyboard or by clicking Start then Settings.

Opening the Windows 11 Settings app from the Start menu

2. In the menu on the left, click Privacy & security. Then, click Windows Security on the right side.

Navigating to Privacy and security settings in Windows 11

3. Click the Open Windows Security button.

Clicking the Open Windows Security button in Windows 11 settings

Managing Firewall Settings

In the new window, click Firewall & network protection. You will see three types of networks:

  • Domain network: Used for office or business computers.
  • Private network: Used for home or trusted work networks.
  • Public network: Used for places like airports or coffee shops.

Note: Changing these settings requires admin privileges.

Click on each network profile to turn the firewall on or off.

Accessing the Firewall and network protection menu in Windows Security
Configuring the Domain network profile settings for Microsoft Defender
Adjusting the Private network profile settings in Windows Security



Managing Virus Protection

1. Click Virus & threat protection in the left menu.

2. Click Manage settings.

3. Toggle Real-time protection and Cloud-delivered protection to the On position.

Managing Virus and threat protection settings in Microsoft Defender

You can also check App & browser control to ensure your settings are active.

Configuring App and browser control settings for Windows 11 security

Summary

Microsoft Defender is vital for keeping your Windows 11 PC safe from malware. You should keep it enabled unless you have installed a different security program that conflicts with it. You can manage these settings easily through the Privacy & security section in your Windows Settings. Regularly checking these options ensures your computer stays protected against new threats.

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Tags: #Windows 11
Richard

About the Author

Richard

Tech Writer, IT Professional

Richard, the owner and lead writer at Geek Rewind, is a tech enthusiast passionate about simplifying complex IT topics. His years of hands-on experience in system administration and enterprise IT operations have honed his ability to provide practical insights and solutions. Richard aims to make technology more accessible and actionable. He's deeply committed to the Geek Rewind community, always ready to answer questions and engage in discussions.

14 responses to “How to Activate Microsoft Defender in Windows 11”

  1. I get an error saying: “You will need a new app to open this windowsdefender link”. All my options are to open the Microsoft Store which does not give any other options after all.

    • I have same issue, and i am still searching solution. I found one more thing Windows defender service is stopped and it is not getting started.

  2. Hi .. I can’t open Windows Sercurity .. it doesn’t run any progress … and I don’t see protection arena like pic.2

  3. Enable the service 🙂
    Service.msc in the search bar
    Find the windows Defender process and enable is click on start and that problem is gone.

    • Not true. Mine starts and stops immediately thereafter. An sfc /scannow shows no issues. I also have Malwarebytes installed and I know it likes to disable Windows Defender but that should not stop me from enabling it again.

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