Liam Hall, 33, shattered bones in his victims’ faces after knocking them unconscious, and left his 24-year-old girlfriend with serious injuries.
Hall was high on drink and drugs when he launched the attacks after getting angry about losing his wallet.
Hall, who previously killed a man in a pub fight, must serve at least 16 years, Teesside Crown Court ruled.
The cagefighter, who weighs 20 stone and is 6ft 4in tall, started dating the woman after being released from prison in May.
In September, he launched the attack on the woman and two unrelated teenage girls at his partner’s home in Chilton, County Durham.
Jolyon Perks, prosecuting, told the court Hall banged one girl’s head against the wall, then grabbed the other and choked her unconscious.
He also punched her repeatedly in the face and stamped on her face, and she later recalled choking on blood.
Hall, of Jade Walk in Chilton, broke her eye socket, nose and arm, and a consultant later said she had too many injuries to count.
The other 13-year-old was also knocked unconscious and she later recalled Hall dragging her upstairs by the hair.
Another child witnessed the scene and ran home hysterically to raise the alarm, telling her mother “there’s blood everywhere”, the court heard.
Hall left his partner with broken bones and serious facial injuries, the court heard.
Each of his victims had statements read for them in court which detailed their ongoing trauma.
One girl said: “I look in the mirror and I think I just don’t recognise myself.”
The other said: “I cannot remember everything. I think it would be better if I had remembered, it bothers me.”
Hall admitted two counts of causing grievous bodily harm with intent, and one of attempting to cause grievous bodily harm with intent.
His barrister John Turner said Hall could not remember the incident but had expressed remorse.
Recorder Jo Kidd dismissed the defendant’s claims of remorse and said that following his release from prison for other violent offences he was a “ticking timebomb”.
She said the attack was unprovoked, on children, and was “grave and gross”.
“Your relative size and weight by comparison to these children cannot be under-estimated,” she said, adding: “In light of your previous conviction for manslaughter, where you killed a man by punching and kicking, you should have been only too aware of the risk you posed to anybody, but particularly children, if you chose to behave in that way again.”
The judge ordered him to serve at least 16 years before being eligible for parole and imposed an indefinite restraining order regarding his victims.
