"The Masterpiece" Chris Masters made his debut in WWE on Raw as a villain, drawing attention to his physique in bodybuilding poses during his entrance to the ring. On the February 21, 2005 episode of Raw, Masters made his debut by defeating Stevie Richards. During the contest, Masters broke Richards' nose performing the Polish Hammer.
Masters made a claim that his version of the full nelson hold, which he dubbed the Master Lock, was unbreakable. Masters began a series of contests he would call "Master Lock Challenges" where Masters would put an opponent in the Master Lock and the opponent would try to break free before Masters made him submit or pass out. Originally he would call out plants from the crowd, placing a $1,000 prize of his own money to be paid to anyone who could break free from the Master Lock. At WrestleMania 21, Masters competed in a 30-man battle royal when he eliminated eight men making it down to the final two where he was eliminated by Booker T. At Backlash, he defeated Melissa Coates in a Master Lock Challenge. He engaged in feuds with lower-card wrestlers, Val Venis and Sgt. Slaughter, who both failed to break the Master Lock. Using villainous tactics, he often attacked the wrestlers beforehand and frequently cheated (for example using a low-blow to escape Sgt. Slaughter's cobra clutch). Masters increased the offered reward each week up to $20,000 and sometimes threw in a bonus. After defeating the 400-pound Rosey on July 18, Masters defiantly stated "it doesn't matter how big they are!", prompting The Big Show to accept a Master Lock Challenge. In accordance with his villainous persona, Masters fled, refusing a match with the Big Show.
In late August, Masters entered a feud with Shawn Michaels, leading to a tag match between himself and Carlito against Ric Flair and Michaels. During the match, Masters defeated Ric Flair by submission. Masters regularly teamed with Carlito, albeit in a rigid business relationship. Michaels competed in a Master Lock Challenge on September 5. Masters, upset at the vigorous resistance of Michaels, released the hold and beat him with a steel chair before re-applying the hold. The Master Lock Challenge, which had not decided a clear victor between the two, led to a match at Unforgiven, which Michaels won.
Masters, alongside fellow Raw wrestler Edge, was one of several wrestlers to "invade" SmackDown! in preparation for the match between the SmackDown! and Raw brands at Survivor Series. The two ambushed Rey Mysterio, leading to a tag match at Taboo Tuesday against Mysterio and Matt Hardy. Edge chose not to participate, so Masters teamed with Edge's replacement, Gene Snitsky. Masters and Snitsky lost when Mysterio pinned Masters. At Survivor Series, Masters competed in a five-on-five Survivor Series match between SmackDown! and Raw wrestlers. During the match, there appeared to be a near-break in the Master Lock by Bobby Lashley, who "powered out" of the hold. As the hold was never completely locked in, however, the "Master Lock" had not been officially broken. Masters was eliminated by Rey Mysterio.
Masters had his first WWE Championship match on the November 28 episode of Raw. It was a triple threat submission match with Kurt Angle and John Cena. The idea was that both Masters and Angle had a submission finisher, and Cena did not (at that moment), so therefore, Cena could not win. Prior to the match, Masters made headlines after attacking then-champion Cena from behind following one of Cena's matches. Masters applied the Master Lock hold, and became the first wrestler to bring Cena to unconsciousness, as Cena was unable to break the hold. During their match, Masters was struck with a chair shot from Cena, who ultimately retained the title, forcing Masters to tap out to Cena's STFU.
Masters portrayed the role of a bailiff during the mock trial for then-General Manager Eric Bischoff on the December 5 episode of Raw, with WWE Chairman Vince McMahon as judge.
On December 12, Chris Masters defeated Viscera on an episode of Raw to gain a spot in the Elimination Chamber match for John Cena's WWE Championship at New Year's Revolution. Viscera was shown to be too big to cinch on the Master Lock until being grounded. On the December 26 episode of Raw, Masters faced Chavo Guerrero in a Beat the Clock match to determine who would be the final entrant to be released from his pod in the Elimination Chamber. Masters had to defeat Guerrero in 5 minutes and 56 seconds, which was the time set by Michaels (when he defeated Snitsky in the opening match of the show). Guerrero managed to survive the Master Lock long enough so that Masters was unable to beat the clock. At New Year's Revolution, Masters was eliminated from the Elimination Chamber match when Carlito double-crossed him by delivering a low blow while he had Cena in the Master Lock and then used a roll-up for the pin. On January 9, after some heated words with Carlito, both men had a tag match against two men who were also having difficulties, Kurt Angle and Shawn Michaels. During the match, Michaels walked backstage, leaving Angle to fend for himself. Masters saw the opportunity and applied the Master Lock to Angle, thus gaining the victory. On January 16, Masters challenged Cena to take part in a Master Lock Challenge. Cena accepted the challenge and displayed signs that he might in fact break out of the hold, until Edge attacked Cena with his title belt and ended the challenge.
At the Royal Rumble, Masters again worked together with Carlito, but Carlito again double-crossed him and eliminated him from the match. On the February 6 episode of Raw both men were entered into a Road to WrestleMania Tournament, to determine the number one contender for a WWE Championship match at WrestleMania 22. In Masters' first round match up he would use the ropes for leverage in a victory against Kane to secure himself a place in the second round against the winner of a later match between Carlito and Rob Van Dam. Van Dam won that match. The next week on Raw, Van Dam was able to beat Masters and advance to the tournament final. After this, Masters continued to feud with one half of the World Tag Team Champions, Big Show, while Masters' on and off teammate Carlito would feud with Kane. On the February 27 episode of Raw, McMahon offered Shawn Michaels' former tag team partner Marty Jannetty a WWE contract in exchange for kissing his exposed buttocks in the middle of the wrestling ring. When Jannetty hesitated, McMahon changed the condition to winning a Master Lock Challenge, and summoned Masters to the ring. After applying the Master Lock, McMahon ordered Masters to force Jannetty's face against his buttocks. Masters failed to complete this instruction as Shawn Michaels interrupted and knocked out Masters. Michaels was then attacked by Shane McMahon, who forced him to kiss Mr. McMahon's buttocks instead. On the March 6 episode of Raw, McMahon publicly thanked everyone who encouraged the previous week's events, and officially awarded Masters and Carlito a World Tag Team Championship match at WrestleMania 22. At WrestleMania 22, the pair lost the match to Big Show and Kane. The pair argued amongst themselves after the match. Even though Carlito had repeatedly betrayed Masters over the previous months, it was Carlito who turned face. During the next Raw, Masters began to feud with Carlito after Carlito attacked him from behind. This led to a match between the two men at Backlash, which Carlito won.
After this, Masters pursued the WWE Intercontinental Championship but would take a hiatus. Before leaving, Masters was on the May 22 episode of Raw, losing a match to John Cena despite low blowing John Cena for two times in a row. On the August 28 episode of Raw, Masters made his return against Cena. Along with less muscle mass, he sported a goatee and mustache leading Jerry "The King" Lawler to refer to him as a "leaner and meaner" Chris Masters. This change of image was short-lived, however, as Masters shaved the goatee and regained some of his muscle mass. When Masters returned, he was put in lower-card matches including a short feud with Super Crazy, who had moved from SmackDown!, with Masters coming out on the losing end of their matches. The pair would also compete in a losing effort, along with four other superstars, in a six-pack challenge for the Intercontinental Championship. Masters gained his first victory since his return against Jerry Lawler on the November 6 episode of Raw in a match where Eric Bischoff, General Manager for the night, forced Lawler to be first handcuffed to the top rope. Masters continued the feud with Lawler for a few weeks with Lawler also losing a Master Lock Challenge before defeating Masters.
On the December 4 episode of Raw, Jonathan Coachman set up a Master Lock Challenge against John Cena for the WWE Championship. Masters appeared to have the challenge won, but he released the hold for a short time, allowing Cena to reverse the hold into his own Master Lock, forcing Masters to submit, retaining his title, and making Cena the first to win the Master Lock Challenge. At the start of 2007, Masters would restart his feud with Carlito, which led to several matches between the two. The first was a one-on-one contest at New Year's Revolution won by Masters. In a rematch the next night on Raw, Carlito came out victorious. On the January 15 episode of Raw, Ron Simmons, with interference from Super Crazy, almost "won" the Master Lock Challenge. An attempted Master Lock Challenge for The Great Khali on the February 26 episode of Raw did not occur when Masters was unable to apply the hold to Khali. The Master Lock was first officially broken on the March 19 episode of Raw, by ECW World Champion Bobby Lashley, after Masters debuted it more than two years prior.
In May and June, Masters challenged Santino Marella for the Intercontinental Championship, losing four times via roll-up. However, on the May 28 episode of Raw, he defeated Marella in the Master Lock Challenge.
On the June 11 episode of Raw, Masters was drafted to the SmackDown! brand as part of the 2007 WWE draft. While on SmackDown! he was used sporadically including a few Master Lock Challenges. He had entered into a feud with Chuck Palumbo, competing in several matches and an attempted Master Lock Challenge that did not begin as Masters fled the ring after Palumbo realized Masters was trying to trick him. Following this, Masters was suspended for 30 days for failing the WWE Wellness Policy. Masters returned to SmackDown! on October 5, applying the Master Lock to Palumbo. Masters suffered a dislocated elbow during his last match, which would have sidelined him for four months. On November 2, 2007, it was reported that Masters had been suspended for 60 days for having violated WWE's Wellness Policy a second time. Six days later, Masters was released from his WWE contract on November 8, 2007.
Masters returned to World Wrestling Entertainment on July 27, 2009. He faced Montel Vontavious Porter in a match that resulted in a double-countout after he applied the Master Lock submission to MVP outside the ring A mini feud continued between the two as Porter was able to score a pinfall victory over Masters the following week to end the feud.
In November 2009, Masters began a face turn, entertaining fans with a pec dance. On the November 2 episode of Raw, Masters entered the Raw's Got Talent show hosted by guest host Ozzy Osbourne, Sharon Osbourne, and The Great Khali, where he performed a "special performance art piece"; he flexed his pecs to the beat of Ozzy's song "Crazy Train", earning a positive crowd reaction. On the December 7 episode of Raw, Masters cemented his face turn by saving Eve Torres and Hornswoggle from Chavo Guerrero after applying the Master Lock. After that, Masters and Torres began an on-screen relationship.
Masters mostly engaged in lower-card feuds throughout 2010 and 2011. Following WrestleMania XXVI, Masters was not active on-screen for over 30 days.
Masters was drafted back to the SmackDown brand on April 26 during the Supplemental Draft. In his first match on the brand, he defeated Chavo Guerrero. Masters found himself lossless in singles matches from May to September, winning eleven singles matches during that period, where all the matches took place on Superstars. Masters was announced as one of the men to compete in the traditional Survivor Series elimination tag team match as part of Team Mysterio, teaming with Rey Mysterio, Big Show, Kofi Kingston and Montel Vontavious Porter to take on Team Del Rio (Alberto Del Rio, Tyler Reks, Jack Swagger, Drew McIntyre and "Dashing" Cody Rhodes). On the November 19 episode of SmackDown, Masters lost to Swagger in a Survivor Series showdown match. Later that same night, he competed in a 10-Man Survivor Series showdown battle royal where he eliminated Rhodes, though later on in the match he was eliminated, the battle royal was won by Mysterio and Big Show (as it was a team versus team battle royal). At the Survivor Series pay-per-view, Masters was eliminated by Del Rio, but his team still went on to win. In late 2010, Masters mentored Byron Saxton on NXT. In February and March 2011, Masters would feud with Tyler Reks on Superstars, and Masters won all four matches they had with each other.
On April 26, 2011, Chris Masters was drafted back to the Raw brand as part of the 2011 Supplemental Draft, but never wrestled on Raw in his four months as a Raw wrestler. His last appearance on WWE programming was against Jack Swagger on the August 4, 2011 episode of Superstars in a losing effort. On August 5, 2011, Masters was released from his contract by WWE.