How to scan a Windows 11 PC for viruses with Windows Security
2 min read · 7 steps · Updated 2 October 2026
Open Start, type Windows Security and open the app. Click Virus & threat protection and then Quick scan. For a thorough check, click Scan options and choose Full scan, or Microsoft Defender Antivirus (offline scan) for malware that hides while Windows is running.
Windows 11 comes with its own antivirus, Microsoft Defender, inside the Windows Security app. It runs in the background all the time. A manual scan makes sense when the PC behaves oddly or after you opened a file you do not trust.
These steps are for Windows 11.
Step by step
Open Windows Security
Click Start, type Windows Security and press Enter. Then click Virus & threat protection.
Run a quick scan
Click Quick scan. It checks the places where malware usually settles and takes a few minutes.
Run a full scan if needed
Click Scan options, select Full scan and click Scan now. It checks every file and running program on the PC and can take an hour or more. You can keep working.
Scan one folder or drive
Under Scan options, choose Custom scan and pick the folder, for example a USB stick. You can also right-click a file or folder in File Explorer and choose Scan with Microsoft Defender.
Use the offline scan for stubborn malware
Choose Microsoft Defender Antivirus (offline scan) and click Scan now. Save your work first: the PC restarts, scans before Windows loads, and starts again. It takes about 15 minutes.
Look at the results
Back in Virus & threat protection, click Protection history. It lists what was found and what Windows did with it: removed, quarantined or allowed.
Check that protection is up to date
Under Virus & threat protection updates, click Protection updates and Check for updates. Under Manage settings, Real-time protection should be on.
Good to know
If another antivirus program is installed, Defender steps back and that program is in charge. Two real-time scanners at once slow the PC down.
Real-time protection can only be switched off for a short time. Windows turns it back on by itself.
After an infection, change the passwords of your important accounts from a clean device, and install all updates: how to check for updates on Windows 11.
If the PC is still unstable, see how to start Windows 11 in safe mode.
In short: Windows Security, Virus & threat protection, Quick scan. Scan options for Full, Custom or offline scan. Results under Protection history.
- Microsoft Support: Virus and Threat Protection in the Windows Security App
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