Boykin was arrested and charged in March after his girlfriend accused him of beating her severely at his home in North Texas.
Police in Mansfield, Texas, said they reviewed footage of a March 21 incident captured by Boykin's security video system. He allegedly broke Shabrika Bailey's jaw, which was swollen and wired shut after the incident.
Boykin, who has denied the allegations, was released from the Seahawks' 90-man offseason roster shortly after the incident came to light.
Aggravated assault causing serious bodily injury is a second-degree felony punishable by two to 20 years in prison.
The quarterback has a history of arrests. He was arrested in Dallas in 2017 when a vehicle he was a passenger in hit several people on a sidewalk. He fled the scene on foot but later was arrested on misdemeanor charges of public intoxication and possession of marijuana.
In 2015, Boykin was arrested for assaulting a police officer and public intoxication shortly before the Alamo Bowl in San Antonio during his senior season at TCU. He was suspended for the bowl game.