Opening OneNote .one Files on OneNote for Mac

To open .one backup files in OneNote for Mac, you need to be on at least OneNote version 16.69 (earlier versions may also work, but it's verified on this version and above). Then:

1. In OneNote, open OneNote Preferences

2. Select Backups

3. Open Backup Folder

4. Create a new folder inside the "Backup" folder

5. Copy your .one file(s) (or subfolders with .one files) into this folder

6. In OneNote, go to the menubar and select File ->Open Backup
   

7. In the file selection window that pops up:

   1. Choose "Other locations" -> Backups
      

   2. Choose the .one file you want to import

   3. You should then see "Open Sections"

8. Right click on the section page

   1. Select Copy Selection to …

   2. Choose your actual notebook