Floyd Mayweather Jr. -- The Mug Shot

TMZ has obtained the mug shot for Floyd Mayweather Jr. -- snapped moments after the boxing champ turned himself in to a Vegas jail this morning.

Floyd is currently serving out a 90-day jail sentence for beating up his baby mama in front of their children in 2010.

While in jail, Floyd will be kept in protective custody, which means he will be kept from the general inmate population.

Floyd's cell is 7' x 14' and contains a bed, toilet, sink and small desk. He also gets a WINDOW.