Northcutt has been training MMA since the age of 4 and competed all over the world from a young age. His father, Mark, is a black belt in shuri-ryūkarate, and his older sister, Colbey, is an amateur kickboxing champion and a professional mixed martial artist currently signed to ONE Championship. At the age of 9, Northcutt became the youngest person ever to be on the cover of Sport Karate Magazine. Northcutt has won a total of 77 world youth championships in karate. He was also an undefeated kickboxer, with his record standing at 15–0. Northcutt attended Seven Lakes High School for his first two years of high school before transferring to Katy High School during his sophomore year. Northcutt was inducted into the Black Belt MagazineHall of Fame in 2012 at age 15.
In 2013, Northcutt began competing on the Legacy Fighting Championship amateur mixed martial arts series, amassing an amateur record of 5-1 with his only loss coming on his first bout against Charles Sheppard by technical-knockout in the first round. At the age of 18, he turned pro and racked up a 5–0 record in 16 months.
Ultimate Fighting Championship
Northcutt was featured in the debut episode of Dana White'sLooking For A Fight. After a victory at Legacy Fighting Championship 44, he was signed to the UFC. In his UFC debut, Northcutt also made his lightweight debut when he faced Francisco Treviño on October 3, 2015, at UFC 192. He won via technical-knockout in 57 seconds. Northcutt's second UFC fight was against Cody Pfister on December 10, 2015, at UFC Fight Night 80. Northcutt won the fight via guillotine choke in the second round. Northcutt was expected to face Andrew Holbrook on January 30, 2016, at. However, after Holbrook withdrew from the bout citing an injury eight days prior to the event, Northcutt would instead make his welterweight debut against Bryan Barberena. Northcutt lost the bout via submission in the second round. Northcutt made a return to lightweight and faced Enrique Marín on July 9, 2016, at UFC 200, where he won via unanimous decision. Northcutt had his second welterweight bout when he faced Mickey Gall on December 17, 2016, at. He lost the contest via submission in the second round. Northcutt was expected to face Claudio Puelles in a lightweight bout on July 29, 2017, at UFC 214. However, Puelles pulled out of the fight in mid-June citing injury and was replaced by John Makdessi. In turn, the fight was canceled on July 14 due to injuries to both fighters. Northcutt faced Michel Quiñones on November 11, 2017, at UFC Fight Night 120. He won the fight via unanimous decision. Northcutt faced Thibault Gouti on February 18, 2018, at UFC Fight Night 126. He won the fight via unanimous decision. Northcutt faced Zak Ottow on July 14, 2018, at UFC Fight Night 133. He won the fight via knockout in the second round. Appearing on The Ariel Helwani Show early September 2018, Northcutt confirmed his contract expired following the fight with Ottow, making him a free agent. In the same appearance, Northcutt said he planned to listen for offers from various promotions. On November 26, 2018, Dana White confirmed on UFC Unfiltered that the UFC did not opt to renew Sage Northcutt's contract. White cited reasons, claiming, "Sage is young, and Sage needs some work. Let him get some work in some other organizations, and we will see where this kid ends up in a couple of years. Maybe we will pick him back up again."
ONE Championship
On November 30, 2018, it was announced that Northcutt had signed with ONE Championship. On February 26, 2019, it was announced that Northcutt was scheduled to make his promotional debut against Cosmo Alexandre on May 17, 2019, in. Northcutt lost the fight by knockout 29 seconds into the first round, marking his first professional loss by knockout. The blow resulted in eight facial fractures which required prompt surgical repair. On November 22, 2019, Northcutt announced that he would be moving down two weight classes to compete at Featherweight in ONE Championship. “I learned my lesson about fighting a weight class too big, going back down to 155, and it’ll be better for me,” Northcutt said in an interview with MMA News.
