Jon Jones employed a guillotine choke to submit Ciryl Gane in the first round of the UFC 285 main event on Saturday night in Las Vegas, claiming the vacant heavyweight title.
Jones becomes the eighth fighter in UFC history to win titles in two divisions.
Also, Alexa Grasso submitted Valentina Shevchenko in the fourth round in a stunning upset to become the new women's flyweight champion.
Jones, who vacated the 205-pound title to move up to heavyweight, submitted Gane at 2.04 of the opening round for his first submission in 11 years.
"I've been working for this for a long time," Jones said afterward. "A lot of people thought I wasn't coming back. I've been faithful to my goal. I've been faithful to the mission. There were days I didn't want to train and I was always there."
Jones had not fought since February 2020.
Grasso submitted Shevchenko at 4.34 of the fourth round with a rear naked choke. Shevchenko had successfully defended her title seven times.
"Please punch me, I feel like I'm dreaming," Grasso said. "I've been dreaming for this moment for so long."