3:31 PM PT -- Mansield PD just released a statement saying the alleged assault was captured on video cameras inside the residence.

Detectives got a search warrant last week, and seized the footage. MPD says they reviewed the footage today ... before an arrest warrant was issued for Boykin.

Cops say Boykin was arrested at his home -- without incident -- and transported to jail.

Bond has not yet been set.

NFL QB Trevone Boykin is in custody after being arrested Wednesday for allegedly punching his girlfriend and cracking her jaw ... TMZ Sports has learned.

Boykin was being investigated by cops in Mansfield, Texas after he was allegedly involved in an altercation with his longtime GF, Shabrika Bailey, last Wednesday.

He has been arrested for aggravated assault with serious bodily injury.

TB -- who was cut by the Seahawks on Tuesday -- vehemently denied any involvement in a physical fight with Bailey.

However, Bailey -- in an interview -- told a different story, claiming Boykin choked her and broke her jaw before finally taking her to the hospital for treatment.