The UFC signed 20-year-old Sergio Pettis to its ranks after amassing a flawless 9-0 MMA record. He was the youngest fighter on the current UFC roster when he took on Vaughn Lee at UFC 167, and he was also among the youngest to have ever competed in the promotion.
We at MMA Insight have compiled a list of six of the youngest fighters to have ever fought for the UFC, and Pettis will be in a group of other stellar MMA stars.
Dan Lauzon
The younger brother of UFC lightweight Joe Lauzon, Dan Lauzon, made his UFC debut as an 18-year-old against Spencer Fisher at UFC 164. It may have been a fight he lost, but Lauzon has had a reasonably solid MMA career in the seven years since then.
He won eight straight MMA fights between 2007 and 2009, resulting in a second UFC shot. That did not go well for the younger Lauzon, having lost back-to-back fights with Cole Miller and Efrain Escudero.
However, he has not lost a fight since then, racking up five wins in a row and has now found a home at the World Series of Fighting (WSOF).
Vitor Belfort
Belfort made his UFC debut all the way back in 1997 as a 19-year-old and was instantly touted as a future star after taking out Tre Telligman and Scott Ferrozzo in one night to win the UFC 12 heavyweight tournament.
Sixteen years and 32 fights later (he was 1-0 before his initial UFC fight), ‘The Phenom’ has had a fantastic career and become one of the best-known fighters in the sport.
Along the way, he’s fought in just about all of the top-level promotions, including the UFC, Pride, Strikeforce and Affliction in three different divisions and gone to war against many of the biggest names like Jon Jones, Anderson Silva, Alistair Overeem, Dan Henderson, Tito Ortiz and Randy Couture.
Robbie Lawler
Welterweight Champion ‘Ruthless’ Robbie Lawler may be 34, but he already has an MMA career spanning over a decade. He made his UFC debut a little after his 20th birthday with a win against Aaron Riley and racked up a three-fight-winning streak with the promotion.
Lawler would later fight in organizations like Pride, EliteXC and Strikeforce, where he cemented his reputation as an exceptionally hard hitter and entertaining striker.
It is a reputation he has brought with him in his second stint with the UFC, and having stopped Josh Koscheck and Bobby Voelker in his return to the promotion so far, he’s positioned himself as one of the top contenders at 170lbs.
Nick Diaz
The notorious welterweight from Stockton, California, had his first fight in the UFC in September 2003, about eight weeks after his 20th birthday.
He had a relatively successful UFC career between then and 2006 before he moved on to test his skills in other organizations, including Pride, EliteXC, Dream and Strikeforce.
Diaz’s Strikeforce stint helped propel him into MMA stardom, having won the Strikeforce Welterweight title and defending it on three straight occasions. He has had mixed success in his return to the UFC, but overall, Diaz has had a highly memorable and distinguished MMA career.
Max Holloway
Holloway wasn’t originally slated to enter the UFC so early in his career, but when Ricardo Lamas pulled out of his fight with Dustin Poirer at UFC 143, Holloway took the call to replace him. He was exactly 20 years and two months old when his UFC debut occurred.
He may have lost that fight, but he has since fought five times in the UFC, going 3-2 in those bouts and generally looked very impressive and surprisingly composed for his age.
The Hawaiian native is still only 21 and has many years of MMA ahead of him, and if his first 10 MMA fights have shown us anything, Holloway’s potential is sky-high. 
Michael McDonald
The man known as ‘Mayday’ made his UFC debut at just over 20 years and two months old in a winning effort against Edwin Figueroa.
He won his first four fights in the Octagon in decisive fashion, which earned him a shot at the interim belt, though he came up short against Renan Barao – and there’s no shame in that.
Still just 22, McDonald has a very bright future ahead of him, and it will be no surprise to most if he becomes a champion in the UFC sometime in the future.
