Can I find out online who I have shared files or folders with in Office 365?

You sure can!  Here is how:

See who you're sharing a file with

1. Once online and in One Drive for Business; right-click the file and then click Share.

2. In the Share dialog box, click Shared with.

   

3. If you're sharing with more people than whose names will fit on the card, select the more link at the end of the list of names. You can scroll the list to see all names.

   Tips: If the library you're working in has a Sharing column, you can select the people icon to open the Share dialog box.

   

Want more details?  Head to the Original Microsoft Webpage.