The Seattle SuperSonics drafted Kemp in the first round of the 1989 NBA Draft and he quickly became a force to be reckoned with. Kemp was one of the NBA's premier high flyers with outstanding leaping abilities. At the time, he was the youngest player in the NBA. Half-court lob passes from Gary Payton to Kemp became a regular sight to see. Together with Payton, Detlef Schrempf, Sam Perkins and Hersey Hawkins, they became a highly successful squad. After Kemp's second NBA season, he picked up the nickname "Reign Man" after Sonics announcer Kevin Calabro saw a poster with the name and found it fitting to add to his radio broadcasts. Conflicting accounts attribute this to his love of the Seattle weather as a rookie, as well as his appreciation of the Dustin Hoffman movie "Rain Man.
Kemp's career peaked in 1995-96, when he led the Sonics to a franchise-record 64 wins and their first NBA Finals appearance since 1979. They faced Michael Jordan and the Chicago Bulls, who were coming off an NBA record 72 wins. The Sonics, however, managed to push the heavily-favored Bulls to six games before losing.
Because Kemp was signed long term into 2001 substantially below what other players were getting, Kemp demanded the Sonics restructure his contract. Many pointed out that Jim McIlvaine had signed a substantially larger contract. However, Kemp had signed his contract several years prior to McIlvaine's signing and the rapid rise of the average salaries in the NBA. At the time of the signing of Kemp's contract, the salary and length of the contract was comparable to other star players in the NBA. Nevertheless, the signing of McIlvaine enraged Sonics' fans, who were unhappy they denied the team's star forward a raise while giving a reserve such a large contract. McIlvaine had only averaged 2.3 points and 2.9 rebounds while playing 15 minutes per game in Washington. Kemp was outraged as well and was threatening to refuse to play in the upcoming season, and the resulting tension with management eventually led to a blockbuster three-team trade following the 1996-1997 season that sent Kemp to the Cleveland Cavaliers, Milwaukee Bucks forward Vin Baker to the Sonics, and Terrell Brandon and Tyrone Hill from the Cavaliers to the Bucks.
Kemp played three seasons with the Cavaliers, where he battled weight problems and often appeared to lack the drive that made him such a force in Seattle. Despite this, he posted career-high numbers for points per game. He was then traded to the Portland Trail Blazers after the 1999-2000 season. The trade reunited Kemp with Bob Whitsitt, who had originally brought Kemp to Seattle. However, Kemp's play began to decline significantly. The last few years of Kemp's professional basketball career were riddled with problems stemming from his weight, as well as cocaine and alcohol abuse. His first season in Portland ended early when he entered drug rehabilitation.
Shawn Kemp Jr., his oldest son, recently committed to play basketball for the University of Alabama for the 2009 season. His son is a 6'9" 220LB Center. He is one of the top Center prospects in the nation and had offers from over 20 colleges.
In June 2006, a mere 3 months after he was arrested, the Denver Post reported that Kemp had slimmed down to the playing weight of his all-star days and was determined to join an NBA team, possibly the Denver Nuggets, and finish his career "the right way. The Nuggets ultimately turned their attention away from Kemp, signing power forward Reggie Evans. Kemp drew some interest from the Chicago Bulls in September 2006, but missed his scheduled workout to visit an ailing relative instead.
During halftime of a November 5 2006 Sonics game, Kemp was announced as one of the 16 members of the Seattle SuperSonics' 40-year anniversary team. After having the longest ovation of all the players, Kemp said after the celebration that he will play with a team in Rome and is still considering a comeback to the NBA. Kemp, however, did not secure a position on an NBA roster during the 2006-07 season.