Riddick Bowe I'm Returning To The Boxing Ring!!! ... Fighting In October

We're told the 53-year-old former 2x heavyweight champion has inked a deal with Celebrity Boxing to fight October 23 in Miami.

Bowe -- who last fought to a unanimous decision victory in December 2008 -- does not yet have an opponent.

Back in his day, Riddick was one of the BADDEST dudes in the world. His pro record stands at 43-1 (33 KO's) ... with 1 of those big wins coming at the expense of the legendary Evander Holyfield.