Microsoft Defender Antivirus is built into Windows 11 and is normally active when no other compatible antivirus product is providing protection. You can check its status in Windows Security and turn real-time protection back on when the control is available.
How to Turn On Microsoft Defender Antivirus in Windows 11
Step 1: Open Windows Security
Open Start, search for Windows Security, and launch the app.
Step 2: Select Virus & threat protection
Open Virus & threat protection to see the antivirus provider and current protection status.
Step 3: Open Manage settings
Under Virus & threat protection settings, select Manage settings when that option is available.
Step 4: Turn on Real-time protection
Enable Real-time protection if it is off and Windows allows you to change it. Leave other recommended Defender protections enabled unless you have a specific managed-security requirement.
If another antivirus product is installed and registered with Windows Security, Microsoft Defender Antivirus can change operating mode and some controls may not be available. Do not run multiple real-time antivirus products simply to make every switch appear active.
On a work or school PC, security settings can also be controlled by organizational policy. Contact the administrator rather than trying to defeat those controls.
If Defender Will Not Turn On
Restart Windows, install current Windows security updates, and check Windows Security for another antivirus provider. If you recently removed third-party security software, use that vendor’s official cleanup guidance if remnants are interfering with Windows Security.
Additional Information
Avoid Registry edits, service-disabling scripts, and “Defender control” utilities from unknown sources. Microsoft Defender is part of the Windows security platform, and troubleshooting should preserve rather than weaken the system’s protection.
Matt Jacobs has been working as an IT consultant for small businesses since receiving his Master’s degree in 2003. While he still does some consulting work, his primary focus now is on creating technology support content for SupportYourTech.com.
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