Emma Watson's Graduation -- Cap? Check. Gown? Check. Armed Guard? CHECK!!!

Emma Watson was the safest student to receive her degree from Brown University on Sunday ... because she had her own armed security guard with her in the audience!

Watson was among 2,000 students to graduate this weekend, but we're guessing she was the only one who employed private security ... cleverly disguised in her own cap and gown.

Expecto Patronum only gets you so far.