Malwarebytes vs Windows Defender (Windows Security)
Windows Defender, now called Windows Security, is the antivirus built directly into Windows 10 and 11 at no extra cost. Malwarebytes is a separately installed application. Unlike the other comparisons on this site, these two aren't really competitors in the traditional sense — they're commonly used together, and Microsoft designs Windows Security to detect and step aside for other registered antivirus products.
What each one is, at a category level
| Aspect | Windows Security | Malwarebytes |
|---|---|---|
| Cost | Included with Windows at no extra charge | Free manual tier; paid tier for real-time protection |
| Installation | Built in, always present | Separate download and install |
| Primary strength (generally cited) | Baseline, continuously updated OS-level protection | Detection of adware, PUPs and malware other engines sometimes miss |
| Typical role | Default resident antivirus | Second-opinion scanner or added real-time layer |
How they actually coexist
When you install Malwarebytes, Windows Security typically registers it as a third-party antivirus and can step back from real-time duties if you choose to make Malwarebytes the primary. Many users instead leave Windows Security running as the resident antivirus and use Malwarebytes Free purely for occasional manual scans, which avoids any real-time conflict entirely.
If you want continuous protection from both automatically, that generally means picking one to be primary and using the other as a secondary layer, rather than running two competing real-time engines side by side. See our Malwarebytes for Windows overview for more on this relationship.
When adding Malwarebytes makes the most sense
- A browser is showing unwanted toolbars, redirects or pop-ups that Windows Security hasn't flagged
- You want an occasional second opinion after Windows Security reports a clean scan
- You want the additional exploit and ransomware behavior monitoring included in Malwarebytes Premium
Frequently asked questions
Do I need Malwarebytes if I already have Windows Security?
Not strictly. Windows Security provides continuously updated baseline protection. Many people add Malwarebytes as an occasional second-opinion scanner because it's historically been strong at catching adware and PUPs, but it isn't mandatory.
Will installing Malwarebytes disable Windows Security?
Windows typically disables its own real-time protection when another registered real-time antivirus is active, to avoid conflicts. If you only use Malwarebytes' manual scanner, Windows Security generally keeps running as normal.
Is Windows Security good enough on its own?
It has improved significantly over the years and is generally considered a reasonable baseline by many reviewers, but check current independent lab results if you want an up-to-date view rather than relying on older reputation.
Malware-Bytes.net is an independent information resource about malware protection for Windows. We are not Malwarebytes, and this site is not the official Malwarebytes website or support channel. Malwarebytes is a trademark of Malwarebytes Inc.