To turn on Windows Defender (now called Microsoft Defender Antivirus) in Windows 10, open Windows Security from the Start menu, click Virus & threat protection, then click Manage settings under Virus & threat protection settings. Turn on Real-time protection. If the switch is missing or grayed out, another antivirus program is probably installed and has taken over. Uninstall it, and Defender turns back on automatically.
Here’s how to turn on each protection feature, check that Defender is working, and fix it when it won’t turn on.
How to turn on Microsoft Defender in Windows 10
- Click Start, type Windows Security, and open it.
- Click Virus & threat protection.
- Under Virus & threat protection settings, click Manage settings.
- Turn on Real-time protection. Click Yes if User Account Control asks.
- Also turn on Cloud-delivered protection and Tamper Protection for the best protection.
Check that Defender is working
- Open Windows Security. Green check marks mean you’re protected.
- Click Virus & threat protection > Quick scan to run a scan.
- Click Protection updates > Check for updates to get the latest definitions.
Defender won’t turn on? Try these fixes
Remove other antivirus software
Windows turns off Defender’s real-time scanning when another antivirus is active. Go to Settings > Apps > Apps & features, uninstall the other antivirus, and restart. Some antivirus makers offer a removal tool for leftovers.
Check Group Policy (Windows 10 Pro)
- Press Windows key + R, type gpedit.msc, and press Enter.
- Go to Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus.
- Double-click Turn off Microsoft Defender Antivirus, set it to Not Configured, and click OK.
- Restart your PC.
Check for malware
Some malware turns off Defender. Run Microsoft Defender Offline scan from Virus & threat protection > Scan options. It restarts your PC and scans before Windows loads.
Other fixes
- Update Windows in Settings > Update & Security.
- Repair system files with
sfc /scannowin an admin Command Prompt. - Work or school PC: Your organization may manage Defender. Ask your IT department.
Frequently asked questions
Is Windows Defender good enough?
For most people, yes. It’s free, built in, and regularly updated. Keep Windows up to date and be careful with downloads and email links.
Does Defender turn itself back on?
Yes. If you turn off real-time protection temporarily, Windows turns it back on automatically after a while.
How do I turn Defender off temporarily?
Turn off Real-time protection in the same settings. See how to disable Windows Defender in Windows 10 for details and risks.
Is Windows 10 still getting Defender updates?
Microsoft continues to provide Defender security intelligence updates on Windows 10 for a period after support ended, but the operating system itself no longer gets regular security fixes without Extended Security Updates.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.