Kleiza was born in Kaunas, Lithuania. At 16 years old he moved to the United States where he attended Montrose Christian School and graduated in 2003. He played on the Lithuanian Junior National Team that won the silver medal at the 2003 FIBA Under-19 World Cup. He led the tournament in scoring, averaging 29.1 points per game on 58 percent shooting. As a senior, he was named a third-team Parade All-American.
Kleiza was selected by the Portland Trail Blazers with the 27th pick of the 2005 NBA draft. The Trail Blazers then dealt his draft rights, along with Ricky Sanchez to the Denver Nuggets in exchange for Jarrett Jack. Kleiza was seldom-used in his rookie season. He averaged 3.5 points and 8.5 minutes per game. He improved on his three-point shooting in his sophomore year, making 83–221, after only making two three-pointers in his rookie year. He also saw some more time on the court and averaged 7.6 points on 42 percent shooting in 18.8 minutes per game. After the season, Denver picked up their team option on his contract for another season. Kleiza became a big part of Denver's rotation in the 2007–08 season, mostly backing up Denver's starting small forward Carmelo Anthony. However, he was involved in a lot of trade talks, most notably a trade involving Ron Artest of the Sacramento Kings. On January 17, 2008, Kleiza scored a career high 41 points against the Utah Jazz. His scoring average was up to 11.1 points per game and his shooting percentage was up to 47 percent. Many expected Kleiza to make a similar leap in production in his fourth year in the league. However, most of his season averages were slightly off from the 2007–08 season. He averaged 9.9 points on 45 percent shooting. His minutes dwindled down in the playoffs. The Nuggets' head coach George Karl, said Kleiza played fewer minutes because he is not a playmaker.
On August 10, 2009, Kleiza agreed to a two-year, $12.2 million gross income contract with the Greek League team Olympiacos. He averaged 17.2 points per game and grabbed 6.4 rebounds per game in the EuroLeague, reaching the EuroLeague Finals with the Reds. Kleiza led the league in scoring, thus winning the Alphonso Ford EuroLeague Top Scorer Trophy, becoming the first Lithuanian to do so.
On July 7, 2010, Kleiza terminated his contract with Olympiacos. He was signed by the Toronto Raptors to a four-year, $20 million gross income offer sheet. In January 2011, he suffered a serious meniscal tear in his right knee and was out for the remainder of the 2010–11 season. On February 1, 2011, Kleiza underwent arthroscopic surgery. He returned to court on January 11, 2012 in a game against the Sacramento Kings. In 14 minutes of game action, he scored 10 points, grabbed 3 rebounds and dished out an assist. On July 16, 2013, the Raptors used the amnesty clause to waive Kleiza.
On July 21, 2014, Kleiza signed a one-year deal with the Italian team Olimpia Milano. After the season he withdrew from professionally playing basketball for unlimited period of time due to knee problems, but did not announce his retirement from the sport.
On July 13, 2017, it was announced that Kleiza received part of the BC Rytas shares from Antanas Guoga. He was also named vice president of the club and its sports director. On February 8, 2020, Kleiza announced his decision to leave BC Rytas due to disagreements with other executives of the team. In May 2020, it was announced that Kleiza gave up his shares in the team to other shareholders.
Personal life
Kleiza and his wife, whom he married in June 2014, have one son.
