He made his WWE debut on the January 9, 2003 edition of Velocity under the gimmick of a mascot representing the local sports team of the town in which he was competing. He continued wearing masks for several weeks, each time competing under a different identity. After acting as a telegram deliverer for Big Show to Undertaker, and getting a Last Ride for his troubles, he showed up the following week and began a series of events trying to impress the then General Manager of Smackdown! Stephanie McMahon in order to earn a contract for the WWE. He eventually earned himself a contract on the March 20, 2003 episode of Smackdown! by defeating Shannon Moore. His first major storyline within WWE came on the May 1, 2003 episode of SmackDown!. He adopted the name "Spanky" after he interrupted a promo by John Cena. The two feuded over their similar hip hop gimmicks, until May 22. On October 30, Spanky began teaming with Paul London until January 13, 2004 when Kendrick left WWE.
He made his return during a live event on August 22, 2005, losing in a Fatal Four-Way match for the WWE Cruiserweight Championship. He then reformed a tag team with his former partner Paul London on the September 30 edition of Velocity. On December 16, the pair remade their image, wearing theatrical masks to the ring with matching vests and shorts. They were quickly elevated into the WWE Tag Team Championship picture, receiving a non-title match against WWE Tag Team Champions MNM on the February 10, 2006 edition of SmackDown!, which London and Kendrick lost. On April 7, they faced MNM again, picking up a win in a non-title match. Their storyline feud continued, as London and Kendrick continued their winning streak over the champions, including singles victories for both Kendrick and London on MNM members Johnny Nitro and Joey Mercury, respectively. London and Kendrick won the WWE Tag Team Title at Judgment Day, thus defeating MNM six times in a row in singles and tag team matches altogether.
Their first main competition for the titles came when K. C. James and Idol Stevens defeated the champions in a non-title match, in early August, igniting a storyline feud between the two teams. During the rivalry, WWE Diva Ashley Massaro began accompanying London and Kendrick to the ring, acting as a valet to the team while combating the actions of James and Stevens' manager Michelle McCool.
On October 14, London and Kendrick became the longest reigning WWE Tag Team Champions of all time, surpassing MNM's previous record of 145 days. Despite this, they were still booked as the underdogs in their feuds, and this was shown when they began a losing streak to the team of William Regal and Dave Taylor. Regal defeated both in singles matches and on the December 8 episode of SmackDown!, Kendrick and London lost a non-title tag team match to the duo, although Kendrick beat Taylor on the December 9 episode of Velocity. London and Kendrick had a scheduled title defense at Armageddon, against Regal and Taylor. Before the pay-per-view, the match changed into a Fatal Four Way tag team ladder match with London and Kendrick defending their titles against Regal and Taylor, MNM, and The Hardys. London and Kendrick won the match and retained the titles.
On February 2, 2007, London and Kendrick suffered a non-title loss to the rookie team Deuce 'n Domino. In a title match at No Way Out, London and Kendrick retained the championship. London and Kendrick, however, dropped the championship to them on the April 20 edition of SmackDown!, ending their reign at 331 days (SmackDown! was recorded on April 17). In the storyline, London missed a moonsault from the ring apron to the floor during the title match, injuring his ribs, leaving Kendrick to battle Deuce 'n Domino alone. London and Kendrick unsuccessfully competed for the title on June 1 in a triple threat tag team match, which also involved Regal and Taylor, and lost a rematch on June 15 in a standard tag team match.
Kendrick, along with London, was drafted to the Raw brand on June 17, 2007 during the Supplemental Draft. They won their debut match on Raw against The World's Greatest Tag Team on June 18. They were soon established as a threat to the tag titles, and on the September 3 edition of Raw, they won a number one contender's match for Lance Cade and Trevor Murdoch's World Tag Team Championship. Kendrick and London then worked a feud with Cade and Murdoch, and at a house show on September 5, they defeated Cade and Murdoch to win the titles, only to lose it back to Cade and Murdoch three days later. London and Kendrick continued to feud with Cade and Murdoch and lost to the Tag Team champions at Unforgiven. For the rest of 2007, London and Kendrick mainly competed on Heat or in tag title bouts, until London got injured in late 2007. As a result, Kendrick was mainly used as a jobber on Raw, until London returned at the start of February 2008, although Kendrick still won sometimes on Heat.
In his next storyline, Kendrick abandoned London during a handicap match with Umaga. This abandonment resulted in Umaga performing the Samoan Spike on London, allowing Umaga to pick up the win over the duo. London and Kendrick still teamed together with no apparent dissension rising between the former tag team champions. After defeating Charlie Haas and Robbie McAllister on Heat, London and Kendrick said they were ready to win the World Tag Team Championship. London and Kendrick beat the champions Hardcore Holly and Cody Rhodes next week on Heat in a non-title match. However, they failed to win the World Tag Team Titles on Raw after Holly pinned London.
As part of the 2008 WWE Supplemental Draft, Kendrick was drafted back to the SmackDown brand while London stayed on Raw, thus ending the team. He made his return to the brand on the July 18, 2008 airing of SmackDown! as a major heel, with new ring attire defeating Jimmy Wang Yang with the help of his new bodyguard, Ezekiel, who was later given a surname and became Ezekiel Jackson. Kendrick was later given the name "The Brian Kendrick". On the August 22 edition of SmackDown, Kendrick won a 10 man battle royal to qualify for the WWE Championship Scramble match at Unforgiven. Kendrick failed to win the title at the event, though he did have the longest reign as "interim" champion, which is not officially recognized per the pre-match stipulation. He later teamed with Jackson on many occasions, becoming number one contenders to the WWE Tag Team Championship held by Carlito and Primo, but they never managed to win the championship.
On April 15, 2009, Kendrick was separated from Jackson as he was drafted back to the Raw brand as part of the 2009 Supplemental Draft while Jackson was drafted to the ECW brand. He wrestled his return match on Raw on the April 27 episode, against Kofi Kingston. He won a match on Raw after defeating Carlito on the May 11 episode before declaring his intention to win the Unified WWE Tag Team Championship; in the following weeks, Kendrick tried several unsuccessful pairings. In his final match, he was defeated by Kofi Kingston during cutting a promo on Jerry Lawler. The match was simply Kendrick turning around into Trouble In Paradise. On July 30, 2009, WWE announced that Kendrick was released from his WWE contract.
On the February 18, 2015 tapings of NXT which was filmed Febuary 12, 2015, General Manager William Regal announced Kendrick's return for Febuary 25, 2015 tapings. On February 25, Kendrick (as The Brian Kendrick) made his return to the WWE at the NXT tapings where he lost to Finn Bálor.
On June 13, 2016, Kendrick was announced as a participant in WWE's upcoming Cruiserweight Classic tournament. The tournament kicked off on June 23 with Kendrick defeating Raul Mendoza in his first round match. On July 14, Kendrick defeated Tony Nese in his second round match. On August 26, Kendrick was eliminated from the tournament in the quarterfinals by Kota Ibushi.
On the August 22, 2016 Raw, The Brian Kendrick was announced as part of the upcoming cruiserweight division. On the September 19 episode of Raw, Kendrick made his official main roster return as a heel, winning a Fatal 4-Way match also involving Rich Swann, Gran Metalik, and Cedric Alexander for the right to face WWE Cruiserweight Champion T.J. Perkins at Clash of Champions. At the event, Kendrick lost the match by submission. After the match, Kendrick appeared to embrace Perkins, but headbutted him to the mat. The next night on Raw, Perkins offered Kendrick a chance to redeem himself, but instead attempted another attack, which Perkins was able to counter. On the October 3 episode of Raw, Kendrick defeated Perkins via submission, remaining the No. 1 contender. In the following weeks, Kendrick would continue commentating during Perkins matches before defeating Perkins once again in a six-man tag team match up on the October 17 episode of Raw. A week before the duo's scheduled match at Hell in a Cell for the WWE Cruiserweight Championship, Kendrick lost to Rich Swann with Perkins on commentary. Kendrick then went backstage, found Perkins, and asked him to lay down for him as Kendrick claimed he needed the title more than Perkins. Kendrick won the title from Perkins at Hell In A Cell after feigning an injury and suckering Perkins in thus entering his first reign as the WWE Cruiserweight Champion in the process. His first title defense occurred the following night on Raw against Perkins, where Kendrick intentionally got himself counted out, thus retained the title. Kendrick's next title defense was at Survivor Series in an inter-promotional match against SmackDown's Kalisto; which Kendrick won by disqualification after Baron Corbin attacked both. If Kalisto would have won the title, the entire cruiserweight division of Raw would have moved to SmackDown. On the debut episode of 205 Live on November 29, Kendrick lost the Cruiserweight Championship to Rich Swann, thus ending his title reign at 30 days. On the December 6 episode of 205 Live, Kendrick faced Swann in a title rematch, but failed to regain the championship. Kendrick again failed to capture the Cruiserweight Championship at Roadblock: End of the Line in a triple threat match against Swann and Perkins.