Cleveland sends Zydrunas Ilgauskas and his expiring $11.5 million contract to Washington. Washington also gets a 2010 first-round draft pick from Cleveland along with the rights to Emir Preldzic, who was selected in the second round of last year's draft.
Besides Jamison, Cleveland also will acquire Clippers guard Sebastian Telfair.
"Antawn is a great pro. We are very excited to have an experienced all-star player of Antawn's caliber and character join us," Cavaliers general manager Danny Ferry said in a statement announcing the trade. "He has the ability to add a special, unique dimension to our team with a strong inside presence and the ability to stretch teams defensively, while impacting the entire court. We think he matches the culture we have built, and continue to build, and will fit well with our group on the court and off."
Jamison left the arena shortly before the Wizards game on Wednesday. As he entered his car, all he had to say to reporters was: "Not now."
He did have a message for Wizards fans. "You know I love them more than they love me."
"Antawn Jamison has been the embodiment of leadership on and off the court for this franchise for five-and-a-half seasons and we thank him for all he has done for the Wizards and the city of Washington," said Wizards president Ernie Grunfeld. "Unfortunately, our on-court results have not met our expectations and we felt it was necessary to make changes to improve our future and our financial flexibility. This trade accomplished both of those objectives."
After long-running trade talks with Washington and Phoenix, Cleveland opted for the Jamison deal, leaving the Miami Heat as the only known suitor for Stoudemire in advance of Thursday's 3 p.m. ET trading deadline.
The Cavs have been chasing Jamison since last season and ultimately preferred this trade in part because they did not have to surrender blossoming young forward J.J. Hickson. The Suns were demanding Hickson along with Ilgauskas' expiring salary for Stoudemire.
Washington relented on its insistence for Hickson because the trade brings more deck-clearing payroll and luxury-tax relief after last week's deal with Dallas that sent Caron Butler, Brendan Haywood and DeShawn Stevenson to Dallas.
Jamison should immediately step in at power forward for Cleveland and supply James with another legitimate scoring option as the Cavaliers seek their first championship. Jamison is still owed $28 million over the next two seasons.
Jamison was extremely popular not only with fans, but also with his teammates and the Wizards' late owner Abe Pollin. After Gilbert Arenas was suspended indefinitely early last month, Jamison was the one who was chosen to speak to the crowd before the Jan. 8 game. He apologized for a skit that pantomimed shooting guns, calling it: "very embarrassing."
Now, Jamison is gone and Wizards coach Flip Saunders lauded him.
"He's one of the most professional guys I've ever been around," Saunders said.
Gooden was reportedly seeking a buyout. Unlike his three former Mavericks teammates, he did not practice with the Wizards on Tuesday, but was at shootaround Wednesday morning. He was listed as inactive.
"Basically, we started looking at opportunities to clear cap space for this summer and in the meantime acquire assets that we also liked," Clippers general manager Mike Dunleavy said. "In the last two days, we were able to do that. And it gives us the flexibility to pretty much go in a lot of different directions."
Jamison was an All-Star in both 2005 and 2008, and averaged 20.5 points in 41 games. He missed the first nine games of this season with a sprained right shoulder.
The 33-year-old played his first five seasons with Golden State and after playing the 2003-04 season with Dallas, was traded to Washington. Jamison has a career average of 19.9 points.
Ilgauskas, who is 34, has played his entire 12-year NBA career with the Cavaliers. He was supplanted as the starting center by Shaquille O'Neal this season. He's averaging 7.5 points and 5.3 rebounds this season. His career averages are 13.9 points and 7.7 rebounds.
"Z has been a cornerstone part of this franchise and his jersey will hang in the rafters here some day, not only because of his play, but because of the tremendous person he is and what he has meant to the franchise and the community," Ferry said. "He has represented the Cavaliers, Cleveland and the NBA at a consistently high level for many years. We wish Z and his family the best."
Ilgauskas' agent, Herb Rudoy, told The (Cleveland) Plain Dealer that he would work quickly to get a buyout from Washington. That would free up Ilgauskas to sign with another team -- including re-signing with the Cavaliers, although he'd have to wait 30 days to return to Cleveland.
"I've already heard from a few teams -- good teams -- that are really interested in wanting to talk about Z going to play for them," Rudoy told the paper.
James can become a free agent this summer, leaving this as Cleveland's final shot at a championship before he decides to stay or go. The Cavaliers also had the league's best record last season, when they failed to reach the NBA finals.
Maybe Jamison can help them take that next step.
The 6-foot-7 Thornton has averaged 13.7 in his three-year career with the Clippers.
Telfair, who's 24, will be playing for his fourth team. The former first-round pick has averaged 7.9 points in his career.
Senior writer Marc Stein covers the NBA for ESPN.com. Information from The Associated Press was used in this report.