Move Your Files from Dropbox to OneDrive for Business in macOS
Action
In order to move your files from Dropbox to your OneDrive for Business account, you will first need be sure OneDrive for Business is set to sync your files from your Mac to your OneDrive for Business account.
Note
This process will remove your files from your Dropbox folder as well as from the folders of anyone you have been sharing with via Dropbox. To continue sharing, you will need to set up any sharing from OneDrive for Business afterward.
Instructions
Find your Dropbox folder in Finder by clicking the Dropbox icon in the Menu Bar at the top of your screen and clicking the folder icon.
Select all of the files and folders in your Dropbox folder by typing cmd-a (hold down the command key and then type 'a').
Type cmd-x (hold down the command key and then type 'x') to cut all of the files and folders.
Navigate to your OneDrive for Business folder. You can find this by clicking the OneDrive cloud icon in your Menu Bar at the top of your screen and then clicking Open OneDrive Folder:
Type cmd-v (hold down the command key and then type 'v') to paste the contents of your Dropbox folder into your OneDrive for Business folder. Your items will start to sync with your OneDrive for Business as soon as the paste is complete.