Installing Microsoft Defender on my computer

Question

Installing Microsoft Defender on my computer

Michael Carson 45

I'm not sure it is installed on my new computer. There seems to be a problem for the software to already know I have a Microsoft annual subscription for 5 devices, which will include this new device.

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Answer 1

EmilyS726 264.9K Independent Advisor

Hello,

If this is a Win11 computer, Microsoft Defender Antivirus is already built into Windows and does not need to be installed separately. You can check its status by going to Start > Windows Security > Virus & threat protection.

However, if you mean the Microsoft Defender app included with Microsoft 365 personal/family/premium subscription, open Start and search for Microsoft Defender. If it is installed, open it and make sure you sign in with the same personal Microsoft account that has your Microsoft 365 subscription. The Defender app is not activated until you sign in with the subscribed account. It is also typically not installed automatically by default.

If it is not installed, you can install it from Microsoft here:

https://aka.ms/WindowsDefender

Michael Carson 45 Reputation points

2026-09-08T19:23:29.15+00:00

Thanks (and you are almost certainly 100% right), but because McAfee was pre-installed, the computer wouldn't let me install Microsoft Defender - so I wasn't sure if I was protected by Microsoft or not (I have windows 11).

Several minutes ago, Deepseek provided the clear answer - that was to uninstall McAfee (tricky enough as they really want you not to uninstall and have a few confusing options when you try and do this). Anyway, I succeeded and was then able to install Microsoft Defender.

Thanks for your time.

Michael
EmilyS726 264.9K Reputation points Independent Advisor

2026-09-08T19:30:33.7366667+00:00

Ah wasn't aware you had McAfee installed. Third party antivirus is really not necessary since Windows Defender can do the job too. Glad it is all sorted now.
Michael Carson 45 Reputation points

2026-09-08T19:38:41.3566667+00:00

Thanks again Emily. You weren't to know I had McAfee pre-installed - or inadvertently installed by my Son who set everything up for me on this new Lenovo computer. I'm glad now to have Microsoft Defender.

Answer 2

Bence Weiszmann 1,560

Dear @Michael Carson

You can download Microsoft Defender for Windows from the following link: Microsoft Defender – Microsoft Store

After installing the app, sign in with the same Microsoft account that you used to purchase your Microsoft 365 subscription.

You can check which devices are currently linked to your Microsoft account here: Microsoft account – Devices

Best regards,
Bence

Michael Carson 45 Reputation points

2026-09-08T19:23:08.8066667+00:00

Thanks (and you are almost certainly 100% right), but because McAfee was pre-installed, the computer wouldn't let me install Microsoft Defender - so I wasn't sure if I was protected by Microsoft or not (I have windows 11).

Several minutes ago, Deepseek provided the clear answer - that was to uninstall McAfee (tricky enough as they really want you not to uninstall and have a few confusing options when you try and do this). Anyway, I succeeded and was then able to install Microsoft Defender.

Thanks for your time.

Michael