Microsoft Defender

Microsoft Defender Antivirus is already included with Windows 10 and 11 and requires no sign-up; only the separate multi-device Microsoft Defender app requires Microsoft 365 Personal or Family.

Find the antivirus built into Windows

1. Open Start.
2. Type Windows Security and open it.
3. Select Virus & threat protection.
4. Check the status shown:
   • Green check mark: protection is working and no action is recommended.
   • Yellow or red indicator: open the item and complete the recommended action.

Windows Security includes Microsoft Defender Antivirus, Windows Firewall, and other built-in protections.^1^

If another antivirus product is installed and active, Microsoft Defender Antivirus normally turns off automatically. It turns back on when the other antivirus is removed.^1^

Sign up for the separate Microsoft Defender app

This optional app provides a security dashboard and protection across Windows, Mac, Android, and iOS. It is included with Microsoft 365 Personal or Microsoft 365 Family.^2^

1. If necessary, purchase either:
   • Microsoft 365 Personal
   • Microsoft 365 Family
2. Use a personal Microsoft account when purchasing the subscription.
3. On the Windows computer, open https://aka.ms/WindowsDefender.
4. Select Install in Microsoft Store.
5. Open Microsoft Defender from Start.
6. Sign in with the same personal Microsoft account used for the Microsoft 365 subscription. The app is not activated until that sign-in is completed.^3^

If Microsoft 365 apps are already installed, search Start for Microsoft Defender first—the Defender app may already have been installed automatically. You still need to open it and sign in.^2^

The optional Defender app is not required to receive the antivirus protection already built into Windows.

References

1. Windows Security App Overview | Microsoft Support
2. Getting started with Microsoft Defender | Microsoft Support
3. Installing Microsoft Defender on my computer - Microsoft Q&A