In the basic sense, absolutely yes—which is why Windows 10 and 11 come with in built-in antivirus protection. But while Windows Security performs well, the best third-party antivirus software have even higher rates of detecting threats. The top antivirus apps also offer more control over settings, detailed logs of your PC's activity, a more user-friendly interface, and additional features to strengthen your online security beyond just viruses and malware. So strictly speaking, a Windows PC doesn't need third-party antivirus software, but you can benefit from more comprehensive online protection. (Macs also need antivirus software.)