By TMZ Sports

Former four division world champion Adrien Broner turned himself into cops in Ohio this morning ... for allegedly beating and robbing a man outside a bowling alley with a gun back in January.

TMZ Sports broke the story ... Broner was charged with felonious assault and aggravated robbery in mid-March ... and a warrant was issued.

Broner arrived at the Hamilton County Sheriff's Department Monday morning ... where he was processed, then released.

Broner is believed to have posted a bail amount of $100,000.

Broner fought last Friday night in the headline bout of Premier Boxing Champions on Spike TV from Washington, D.C. He knocked out Ashley Theophane in the 9th round.

After that fight, he publicly challenged former friend Floyd Mayweather Jr. to unretire and fight him in the ring. Broner, who failed to make the junior welterweight limit of 140-pounds last Thursday, is planning to return to the welterweight limit of 147 in his next fight.