Ronda Rousey -- Loses UFC Title Belt ... for Charity

It finally happened ... Ronda Rousey lost her title belt, but in the most awesome way possible.

Ronda happily handed over a UFC Women's Bantamweight belt on Wednesday to a judo school in Rio de Janeiro because she's pretty tight with the instructor and his students.

A UFC spokesman tells TMZ Sports ... Ronda's actually worked out with kids at Instituto Recao in the past, and the guy who runs the place is an Olympic medalist in judo, just like Ronda.

She's reportedly made huge financial donations to the school in the past, but this time she offered up a replica of the belt she retained Saturday night after her 34 second dismantling of Bethe Correia.