Early career Prior to his official professional debut, Diaz engaged in unsanctioned bare knuckle MMA matches. Diaz became a professional mixed martial arts fighter in 2001 just after his 18th birthday and won his first fight, submitting Mike Wick with a
triangle choke at IFC Warriors Challenge 15. Diaz became a champion in his second professional fight, defeating
Chris Lytle for the IFC Welterweight Championship in July 2002 at IFC Warriors Challenge 17. Diaz was then invited to participate in Ultimate Athlete's King of the Mountain, a single-night tournament that took place two months later. He won his first two fights but eventually lost in the finals to
Jeremy Jackson by TKO. Diaz fought in Warriors Quest and
Shooto against Harris "Hitman" Sarmiento and
Kuniyoshi Hironaka respectively before defending his IFC Welterweight Championship and winning the
WEC Welterweight Championship in 2003 at
WEC 6, submitting Joe Hurley with a
kimura. Diaz returned to defend his IFC Welterweight Championship against the man who defeated him one year earlier,
Jeremy Jackson at IFC Warriors Challenge 18. This bout was for Diaz's IFC United States Welterweight Championship, Jackson's IFC Americas Welterweight Championship and the vacant ISKA-MMA Americas Welterweight Championship. Diaz won the rematch via TKO in the first round. Taking notice of his success, the UFC signed Diaz over the summer and he made his debut at
UFC 44, completing the trilogy against Jackson and submitting him with an
armbar in the last round of a back-and-forth fight that Diaz appeared to be winning on the scorecards.
Ultimate Fighting Championship Diaz returned to the Octagon at
UFC 47, set to take on future
EliteXC Middleweight Champion Robbie Lawler. Lawler was a heavy favorite coming into the fight but it was Diaz who took the offensive, chasing Lawler around the cage for the majority of the bout. In the second round, Diaz taunted Lawler, who swung wildly and missed, allowing Diaz to connect with a right hook that knocked Lawler out. Diaz was then matched up with
judoka
Karo Parisyan at
UFC 49, but ended up losing a hard-fought split decision. He rebounded with wins over submission specialist
Drew Fickett at
UFC 51 and Koji Oishi at
UFC 53 before losing for the second time in the UFC at the hands of
The Ultimate Fighter Middleweight winner
Diego Sanchez at
The Ultimate Fighter 2 Finale. Diaz was confident coming into the bout but was unable to achieve success in the match, ultimately losing to Sanchez by unanimous decision. During the televised post-fight interview in the octagon, Diaz continued the controversy by declaring that he respected Sanchez fighting ability but did not think he deserved to be there, despite Sanchez's win. Diaz's next fight was against
Joe Riggs at
UFC 57. Similar to his treatment of Sanchez, Diaz made sure that he taunted his opponent plenty before their fight starting at the official press conference at the event in which Diaz confronted Riggs and the two exchanged words. They continued their conversation at the official weigh-ins in which both fighters had to be separated by UFC president
Dana White and other officials present. Riggs prevailed in a hard-fought battle, winning by unanimous decision and giving Diaz his second straight loss. After the fight, the two were taken to the hospital for observation and post-fight tests, where they had yet another scuffle. Diaz lost his third consecutive match in a unanimous decision to future
UFC Lightweight Champion Sean Sherk at
UFC 59.
Return to UFC Diaz returned to his hometown of
Stockton and participated in the International Cage Fighting Organization's inaugural event, defeating Ray Steinbeiss by unanimous decision. Diaz was slated to fight in his hometown again against
Canadian John Alessio when he received an unexpected call the night before the fight from the UFC asking to fill in for an ill
Thiago Alves at
UFC 62. After Alessio pulled out, Diaz took advantage of the opportunity, submitting veteran
Josh Neer in the third round. Seemingly back in the UFC, Diaz stopped Brazilian newcomer
Gleison Tibau with strikes in his next fight at
UFC 65. However, even after the win and the reassurance that the UFC would give him another fight, Diaz decided to sign with the Gracie Fighting Championships and leave the UFC. GFC had Diaz scheduled to fight Thomas Denny in January 2007, but due to poor ticket sales the event was ultimately scrapped. At the end of the first round, apparently due to poor cardio on Gomi's part, the
Japanese fighter was clearly stunned, throwing much wilder punches and barely maintaining his defense. Early in the second round, the fight was stopped to check a cut suffered under Diaz's eye. The second round saw a continuation of wild punches by Gomi, then eventually taking the fight to the ground and leaving himself open to a
Gogoplata submission by Diaz and tapping at 1:46 of the round. Dr. Alamo went on to say, "Mr. Diaz was 175. This creates a unique situation. I was there at this fight and believe that you were intoxicated and... that it made you numb to the pain. Did it help you win? I think it did." Despite Diaz being surrounded by other athletes and video cameras for several hours before the fight, Alamo gave no explanation for why he believed Diaz had used marijuana in the hours preceding the event. Diaz himself dismissed the assertion that marijuana was a
Performance-enhancing drug, or that he was smoking it prior to the fight.
EliteXC Diaz made his debut for EliteXC in Hawaii on September 15, 2007 on Showtime. He won a hard-fought split decision over his opponent Mike Aina. MMA Weekly reported that Nick Diaz signed a two-year deal with EliteXC and in his next fight, fought
K. J. Noons for the vacant 160 pound title. Once the fight began, the two exchanged rather evenly on the feet until Noons dropped Diaz with a well timed right counterpunch. Diaz attempted several takedowns, all of which were stuffed by Noons, on one occasion with a swift right knee which opened up a notable gash on Diaz's face, eventually resulting in a loss via doctor stoppage due to multiple cuts on his forehead. A disappointed Diaz left the arena immediately and on his way out he flipped off the doctor from the arena entrance and shoved the camera out of his face. After losing to Noons, Diaz had surgery and had the bone filed down on his eyebrows to mitigate any bad cuts in future bouts. Diaz came into his next fight at EliteXC's "Return of the KING" event in Honolulu, Hawaii against Muhsin Corbbrey 9 pounds over the weight limit. Diaz earned a tough win over Corbbrey, following the main event an altercation between Nick and his brother Nate broke out with
K. J. Noons and his corner. EliteXC executives asked Diaz to come to the ring and make a statement about a possible title rematch with Noons. Noons, a native of Hawaii, asked the crowd their opinion, resulting in an echo of boos for Diaz. After Nick spoke over the microphone to Noons, saying, "don't be scared homie," Karl Noons, K. J.'s father, lunged at him prompting Nate Diaz to throw a water bottle at Karl. The Diaz brothers were quickly escorted out of the cage by a group of security staff. During interviews the next day Nick claimed Karl was intoxicated and overreacting. Meanwhile, Karl claimed his incident was prompted by the thrown bottle. Video replay of the event showed Nate throwing the bottle after Karl jumped at Nick. No one was injured as the Diaz brothers left the arena entrance "
flipping the bird" to the fans and Noons's corner. Nick went on to face Thomas Denny. After a sluggish start to the fight, Diaz found his range and dominated Denny during the latter half of the first round. Diaz continued to keep the fight standing and maintained a high-paced tempo for the remainder of the fight, earning an impressive knockout victory over the veteran Denny 0:30 into round two. Diaz was scheduled to face
Eddie Alvarez for the EliteXC 160 pound title on November 8, 2008 before the company ceased operations.
Strikeforce and DREAM Diaz was victorious in
DREAM 3, defeating Katsuya Inoue by TKO in the first round. With
Strikeforce's acquisition of
ProElite's assets, CEO
Scott Coker had announced that Nick would face off against
MMA legend
Frank Shamrock at a Catchweight of 179 lb, at their upcoming event,
Strikeforce: Shamrock vs. Diaz, in Shamrock's hometown of
San Jose on April 11, 2009 at the
HP Pavilion. Nick was successful in the fight, defeating Shamrock via TKO due to strikes in the second round. Throughout the fight, Diaz was dominant in all areas using effective positioning on the ground, once mounting Frank in the end of the first round, before finally finishing the fight in the second round with a body shot that crumpled Frank to the mat and follow up punches before referee
John McCarthy called a halt to the bout. In the interview he stated "It's hard to hate the guy, he's been doing what I've been wanting to do and saying what I've wanted to say for a long time". At
Strikeforce: Lawler vs. Shields Diaz met former UFC veteran
Scott Smith at a Catchweight of 180 pounds. Although Smith took Diaz down once in the first round, Diaz controlled the majority of the bout with his superior boxing, utilizing his reach, stalking jabs and repeatedly punishing Smith with hooks to the body, twice dropping him in the second and third round. Upon landing the body shot that dropped Smith in the third round, Smith assumed a "turtle" position and Diaz took his back until securing a
rear-naked choke to finish the bout at 1:41 of the final round. It was announced that Diaz would be fighting
Joe Riggs at
Strikeforce: Carano vs. Cyborg taking place on August 15, in which would have been a rematch of their first fight that took place at
UFC 57: Couture vs Liddell 3, in which both fighters fought in the cage and then again at the local hospital later in the evening. The fight would have been for the
Strikeforce Welterweight Championship but, Riggs had to pull out of the bout due to an adverse reaction to a drug. Diaz was then scheduled to instead face former
IFL Welterweight Champion Jay Hieron for the
Welterweight Championship. This fight has since been canceled due to Diaz's failure to attain his license after not attending a pre-fight drug test.
Jesse Taylor replaced Diaz and the title was no longer on the line, Hieron defeated Taylor by unanimous decision. Diaz faced Strikeforce newcomer and then-
DREAM Welterweight Champion Marius Žaromskis to crown the first
Strikeforce Welterweight Champion on January 30, 2010 at
Strikeforce: Miami. Žaromskis came out aggressively and the two men exchanged on the feet until Diaz tied his opponent up in the clinch and landed numerous knees to Žaromskis' right leg. Diaz then scored a takedown and looked for a
guillotine choke – quickly shrugged off by his opponent. The two men continued to exchange, with Diaz utilizing his unorthodox boxing skills, until rocked by a Žaromskis left hook and falling to his back. Žaromskis landed few effective shots while Diaz was "turtled" on the floor, allowing him to recover and stand back up. In the few remaining minutes, Diaz opened up with his boxing range, tagging Žaromskis cleanly several times with combos composed of jabs, hooks and seamless bodyshots; forcing him against the side of the cage where he landed a solid uppercut that dropped his opponent leading to the referee to stop the contest at 4:38 of the first round. Diaz was then crowned the inaugural
Strikeforce Welterweight Champion. Diaz defeated former PRIDE veteran
Hayato Sakurai by
armbar submission in a non-title bout at
DREAM 14. Diaz defeated K. J. Noons in a rematch of their 2007 bout for the
Strikeforce Welterweight Championship. Diaz won via unanimous decision (48–47, 49–47, and 49–46). Diaz defeated Brazilian
Evangelista Santos who had an 18–13 MMA record going into the bout on January 29, 2011 at
Strikeforce: Diaz vs. Cyborg via
armbar in the second round. Diaz defeated English fighter
Paul Daley at
Strikeforce: Diaz vs. Daley via TKO (punches) at 4:57 of round 1, and became the first Strikeforce fighter to successfully defend the
Strikeforce Welterweight Champion three consecutive times.
Second return to UFC UFC president
Dana White stated that a matchup between Diaz and
UFC Welterweight Champion Georges St-Pierre was a possible consideration. Diaz and St-Pierre were rumored to be the next coaches for
The Ultimate Fighter 14 reality show, but the show debuted on September 21, 2011, with
Michael Bisping and
Jason Miller as coaches. White later confirmed via
Twitter that Diaz would face St-Pierre at
UFC 137 at the Mandalay Bay Event Center in Las Vegas, Nevada, on October 29, 2011. Nick Diaz vacated his
Strikeforce Welterweight Championship title prior to his bout with
Georges St-Pierre. Dana White made the decision to take Diaz out of the fight and replace him with former
WEC Welterweight Champion and future
UFC Interim Welterweight Champion Carlos Condit, due to Diaz missing multiple flights for a press event to support the fight. It was announced that Diaz would fight
B.J. Penn in the main event at his original fight card,
UFC 137. Diaz won via unanimous decision. Diaz called out St-Pierre in the post-fight interview, who was scheduled to fight Condit at the same event but had been forced out of the bout with a knee injury. Following his successful return, Diaz was expected to face
Georges St-Pierre for the UFC Welterweight Championship at
UFC 143 during
Super Bowl weekend. However, due to an ACL injury sustained by St-Pierre, Diaz faced
Carlos Condit in the main event, with the winner being awarded an Interim UFC Welterweight Championship. Condit defeated Diaz via unanimous decision. Upset with the result of the fight, Diaz indicated that he was retiring from the sport. After the event UFC President Dana White said that he believed Diaz would fight again. Diaz was briefly linked to a rematch with Condit, but was quickly refuted when Diaz tested positive for
marijuana metabolites in a post-fight drug test. The
Nevada State Athletic Commission temporarily suspended Diaz shortly after the positive test, pending a full disciplinary hearing. It was announced at the hearing in May 2012 that Diaz was suspended for one year, retroactive to February 4, 2012, and fined 30 percent of his fight purse earned from the Condit bout. Diaz was eligible to return to MMA competition in February 2013. Diaz faced Georges St-Pierre at
UFC 158 on March 16, 2013 for the UFC Welterweight Championship. He lost the fight via unanimous decision. As of July 28, 2013, Diaz had once again retired from MMA competition, though
Dana White stated in interviews that he felt that Diaz was simply on hiatus, financially sound from the GSP fight, but did expect him to return eventually. A possible
Middleweight matchup between
Michael Bisping and Nick Diaz was briefly linked, but soon turned down by Diaz. At
UFC on Fox 9 in Sacramento, Dana White offered Diaz a rematch with Carlos Condit; Diaz turned it down. Diaz attended
UFC 170 and had told media that he would return if he could get an immediate title shot. On July 24, 2014, it was announced that Diaz had signed a three-fight contract to return to the
UFC. Diaz faced
Anderson Silva on January 31, 2015 at
UFC 183. He lost the fight by unanimous decision. A few days after the fight, the UFC revealed that Diaz had once again failed his post-fight drug test for
marijuana metabolites, and Silva tested positive on January 9 for
drostanolone,
androstane, oxazepam, and temazepam in pre-fight drug screening. On August 13, after several reschedules, Silva's disciplinary hearing was held to decide on the subject. Silva's defense argued that a tainted
sexual enhancement supplement was the root of the two failed tests for drostanolone and also appealed to mistakes in the NSAC testing procedures, pointing to a pair of drug tests, one on Jan 19 and one after the fight, which Silva passed. He admitted to using both temazepam and oxazepam, benzodiazepines, the night prior to the fight as therapy to control stress and help him sleep. Silva's team was unable to explain the presence of androsterone in the Jan 9 test. The commission rejected the defense and suspended him for one year retroactive to the date of the fight, as the current guidelines were not in effect at the time of the failed tests. Silva was also fined his full win bonus, as well as 30% of his show money, totaling $380,000. The result of the bout was changed to a no contest. At that point, Diaz had accumulated a UFC record of 7 wins, 6 losses and 1 no contest, with no successful challenges for a title. On September 14, 2015 the Nevada State Athletic Commission suspended Diaz for 5 years and fined him $165,000 following his failed drug test of
marijuana metabolites at UFC 183. Following his appeal four months later in January 2016, the suspension and fine were reduced to 18 months and $100,000. The suspension was officially lifted on August 1, 2016. Diaz had served a technical suspension due to outstanding fines with the NSAC as stipulated in his settlement claim. For this reason he was unable to corner Nate Diaz during
UFC 196 and
UFC 202. Diaz, according to sources, has reached an agreement with the Nevada Athletic Commission, which now frees him to participate in all combat sport-related activities in the state once again. On April 9, 2018, Diaz accepted a one-year USADA sanction for failing to report his whereabouts to USADA on three occasions from the third quarter of 2016 to the first quarter of 2017. The sanction is retroactive to April 9, 2017, and Diaz would be eligible to compete again on April 9, 2018. After a long hiatus since 2015, Diaz returned to rematch against
Robbie Lawler on September 25, 2021 at
UFC 266. The bout was contested at middleweight and was a special non-title, non-main event five round bout. After a back-and-forth fight, Diaz was knocked down with punches in round three, but was given the opportunity to return to his feet. Diaz stayed down and verbally submitted resulting in a TKO loss. After a three-year absence, Diaz was scheduled to face
Vicente Luque on August 3, 2024 at
UFC on ABC 7. However, due to travel issues, the bout was postponed and was scheduled to take place on December 7, 2024 at
UFC 310. In turn, Diaz withdrew from the bout for unknown reasons and was replaced by
Themba Gorimbo. ==Professional grappling career==