The incident occurred in 2014 when War Machine broke into his ex-girlfriend Christy Mackinday's house and assaulted her and her friend Corey Thomas. Jurors declared a mistrial on the charges of attempted murder and attempted murder with a deadly weapon.
Jurors spent two days deliberating the charges against Koppenhaver, who broke into Mack's house on August 8, 2014 and attacked her and boyfriend Corey Thomas, leaving both with serious injuries. He has been in jail since. Each could get him up to life in prison without the possibility of parole.
According to Antonio Castelan of KSNV, Koppenhaver will be sentenced June 5.
This is a developing story. The beating stopped, he said, when he asked Koppenhaver if his "end game" was going to be to kill him or let him go.
However, the prosecution had painted a detailed picture of the abuse Ms Mackinday faced during their tumultuous 15-month relationship and the love that blinded her to the dangers of Koppenhaver's violent and controlling nature.
Thomas said he allegedly suffered a broken nose, dislocated shoulder, scrapes, bruises and bite marks in the attack. She also had a ruptured liver that prevented doctors from initially operating on her for fear of putting her under anesthesia.
Mack said she fled her home and ran bleeding to neighbors when Koppenhaver went to the kitchen to fetch a knife.
Koppenhaver was arrested a week later in the Los Angeles suburb of Simi Valley, and was returned to Nevada.
Koppenhaver, 35, went by his birth name during the two-week trial but had legally changed it to War Machine during his 19-fight MMA career.
Koppenhaver made his Ultimate Fighting Championship debut in 2007.
He was dropped by his fight promoter and his clothing line after Mack's accusations became public.