Remove Malware from Windows with Microsoft Defender (Full Scan and Offline Scan)

You think your Windows PC might be infected and you want to scan it and clean it up safely, for free, with the protection that’s already built in.

Why: Windows includes Microsoft Defender Antivirus in the Windows Security app. A quick scan checks the usual hiding spots; a full scan checks everything; and a Microsoft Defender Offline scan restarts your PC and scans before Windows loads, so malware that hides itself while Windows is running has nowhere to hide.

Fix 1: Run a full scan

A full scan checks every file and program on your device. It takes a while, so start it when you don’t need the PC for an hour or so.

1. Select Start, type Windows Security, and open it.
2. Select Virus & threat protection.
3. Under Current threats, select Scan options.
4. Choose Full scan, then select Scan now.
5. Let it finish. If it finds anything, follow the on-screen prompts to remove or quarantine it.

A quick scan (the default) is fine for a fast check, but a full scan is the thorough one when you actually suspect an infection.

Fix 2: Run a Microsoft Defender Offline scan

This is the strongest option. It restarts your PC and runs the scan from a trusted environment without loading Windows, which catches infections that hide while Windows is running.

1. Save any open files and close your apps first — your PC will restart during this scan.
2. In Windows Security, select Virus & threat protection > Scan options.
3. Choose Microsoft Defender Offline scan, then select Scan now.
4. Your PC restarts and the scan runs automatically (it usually takes around 15 minutes). The PC restarts again when it’s done.
5. After it finishes, open Windows Security > Virus & threat protection > Protection history to see what it found.

Fix 3: If something keeps coming back

If a threat reappears after you clean it, an unwanted program may be reinstalling it.

1. Go to Start > Settings > Apps > Installed apps and uninstall anything you don’t recognize or didn’t intend to install.
2. Run the Offline scan again from Fix 2.
3. Make sure Windows is fully updated via Start > Settings > Windows Update > Check for updates, since updates include the latest threat protection.

Be cautious here: don’t uninstall drivers or system components you’re unsure about. If you’re not certain a program is safe to remove, search its exact name first.

FAQ

Do I need to buy antivirus to do this? No. Microsoft Defender Antivirus is built into Windows Security at no cost, and the Offline scan is part of it.

Which scan should I run if I’m really worried? Run a full scan first, and if you still suspect something, run the Microsoft Defender Offline scan — it’s the most complete because it runs before Windows loads.

Will the Offline scan delete my files? No. It scans for and removes malware, not your personal documents. Still, save open work before you start because the PC restarts.

Sources: Microsoft Support — Virus & threat protection in the Windows Security app, Microsoft Support — Help protect my PC with Microsoft Defender Offline