A number of fighters have been cut by the UFC over the last year, while many others have left the promotion in search of better pay.
A few fighters like Demetrious Johnson and Ryan Bader have won titles since leaving the UFC, but some have lost their debut fights after leaving the biggest stage in MMA at the moment.
Here are 5 fighters who lost their first fight in another promotion after leaving the UFC.
#5 Chael Sonnen
Technically, Chael Sonnen didn't leave the UFC before he joined Bellator in late 2016. He walked away from the sport in 2014 after failing a couple of drug tests, and took a couple of years off before returning as a light heavyweight under a different banner.
Sonnen had initially joined the promotion way back in October 2005, before leaving in May 2006 and returning during the time of the WEC merger. And after his second stint with the UFC, which saw him record wins over Michael Bisping and Shogun Rua and push Anderson Silva to the limit, it was clear that 'The American Gangster' was far from a spent force.
Sonnen has suffered losses to Jon Jones, Anderson Silva, Rashad Evans and Demain Maia during his second spell with the UFC and was 39 years old, but he was still expected to make a splash at Bellator. However, things went badly for 'The Bad Guy'.
Sonnen appeared to be in poor shape in the lead-up to the fight, with the extra bulk he was carrying at light heavyweight appearing to weigh him down. Tito Ortiz, fighting what was meant to be his retirement fight, locked in a choke halfway through the first round to submit his opponent.
Sonnen went on a fairly impressive two-fight win streak against Wanderlei Silva and Quinton 'Rampage' Jackson, but retired in 2019 after losses to Fedor Emelianenko and Lyoto Machida.
#4 Paige VanZant
Soon after Paige VanZant started her UFC career with three wins on the trot, it became clear that while she had obvious promise, she probably wouldn't be able to remain a serious contender for very long.
VanZant was completely dominated by Rose Namajunas in December 2015, and her career plummeted shortly after the loss. '12 Gauge' suffered reversals at the hands of Michelle Waterson and Jessica-Rose Clark, before an embarrassing loss to Amanda Ribas at UFC 251 pushed president Dana White to release her.
Only 26 years old at the time, VanZant was expected to be a hit at another top MMA promotion, with her obvious marketability and good looks. But she made the curious decision to join the Bare Knuckle Fighting Championship, where she was pitted against Britain Hart in February 2021.
VanZant's BKFC debut didn't go to plan, as she went down to a tight UD loss. She is expected to return to the ring in June this year.
#3 Sage Northcutt
After entering the UFC in 2015 with an unblemished 5-0 record, Sage Northcutt appeared to be well on the road to superstardom. He put together a 6-2 record in the promotion, and seemed ready to be handed a ranked opponent.
But to the surprise of everyone, UFC president Dana White refused to offer Northcutt a new deal, saying the youngster "needs some work". After testing out the waters of free agency, 'Super' signed a deal with ONE Championship.
In his ONE debut in May 2019, Northcutt faced off against powerful Brazilian kickboxer Cosmo Alexandre. The step up in competition proved to be extremely dangerous, as he suffered a brutal first-round KO loss that caused eight facial fractures.
Northcutt was expected to face Shinya Aoki on April 28, but he had to withdraw from the bout due to the lingering effects of COVID-19. It remains to be seen what the future holds for the 25-year-old.
#2 Eddie Alvarez
After making waves at Bellator by winning the lightweight title, Eddie Alvarez joined the UFC amid much fanfare. An accomplished wrestler whose striking had improved significantly with time, 'The Underground King' overcame a loss on UFC debut to Donald Cerrone to clinch the lightweight title with a win over Rafael dos Anjos.
Although he was brutalized by Conor McGregor in his first title defence, there was no doubting the fact that Alvarez was one of the best lightweights on the planet. After running out his UFC contract with a loss to Dustin Poirier, he moved to ONE Championship with the intention of winning the title in three of the world's biggest MMA promotions.
However, things haven't gone to plan for Alvarez at ONE. He was shockingly knocked out in the first round by Timofey Nastyukhin on his promotional debut, and recently suffered a DQ loss to Iuri Lapicus for illegal blows to the back of the head.
#1 Anthony Pettis
One of the most entertaining fighters MMA has ever seen, former UFC lightweight champion Anthony Pettis chose not to renew his contract with the promotion following his UD win over Alex Morono back in December 2020.
'Showtime' joined the Professional Fighters League on his quest for a bigger paycheck, and was pitted against Clay Collard in his promotional debut this week.
Unfortunately, Pettis' PFL debut wasn't a memorable one. He was rocked and dropped by 'Cassius', who survived a late charge from his opponent to clinch a fairly comfortable UD win.
Pettis appears to be well past his prime, but he could still put on a few highlight-reel knockouts for fans to enjoy at PFL.