Because OneNote is deeply integrated into the Microsoft 365 ecosystem and the Windows operating system, Microsoft requires a traditional installation for its desktop apps.

A portable application is software configured to run from a removable storage device, like a USB flash drive, external hard drive, or cloud folder, without writing data to the host computer's registry.

Select the ONENOTE.EXE file (typically found in C:\Program Files\Microsoft Office\root\Office16\ ).

where you can't install software, or are you just looking for a way to keep a physical backup of your notes?

Log in to OneNote.com in a browser (like Chrome or Edge) on the host machine. Ensure you are logged into your Microsoft account.

You maintain the exact same settings, preferences, and organization regardless of which computer you are using.

Microsoft OneNote Portable: Your Complete Guide to Note-Taking on the Go

If you specifically need a version to run from a USB drive on computers where you cannot install software, advanced users use these methods: Introducing OneNote - Microsoft Support

While there is no official standalone "Microsoft OneNote Portable" application released by Microsoft, users often create their own "portable" experience to keep their notes accessible on the go without requiring a traditional installation on every machine The "Official" Portable Experience