A Microsoft file hosting and synchronization service.
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Microsoft’s recommended way to transfer all of your files from your personal OneDrive account to your OneDrive for Business account is to sign in to both accounts in the OneDrive desktop app. Then, move the files from your personal OneDrive folder to your work OneDrive folder. If you have more than 100 GB of data in your personal cloud, Microsoft recommends moving the files in smaller batches instead of transferring everything at once.
Reference:
https://learn.microsoft.com/en-us/microsoft-365/admin/setup/files-to-onedrive?view=o365-worldwide
When syncing, you should see a blue circular arrow icon on the files. Once the files are synced, you will see green check marks on each file. You can then transfer the next batch of files from your personal account.
This is also the easiest way to transfer your files from your business account back to your personal account.
If this is not an option, you will need to look for third‑party cloud storage transfer tools online. These may require a subscription or one‑time payment, and using them is generally not recommended.