NBA Boone was picked 23rd overall in the
2006 NBA draft by the
New Jersey Nets. He was picked right behind former
UConn teammate,
Marcus Williams who was also selected by the Nets. During the 2006 Pepsi Pro Summer League in
Orlando he led the league in rebounding (9 rpg) and was 2nd in blocked shots (1.67 bpg). After the summer league he underwent surgery to repair a torn
labrum in his left shoulder and was expected to be out for 4–6 months, however he returned much earlier. Boone made his NBA debut December 2, 2006, against the
Philadelphia 76ers, playing 2 minutes. Suffering the effects of the injury and missing the pre-season training, Boone had an inconsistent but promising rookie season. Boone averaged 4.2 points per game, 2.80 rebounds per game and 0.3 blocks per game during his rookie season. On December 26, 2006, he had a season-high of 12 rebounds against the
Detroit Pistons, a game in which he played 30 minutes, the most he had played hitherto. Boone had a then career-high 21 points on 10-for-10 shooting, while grabbing six rebounds on March 24, 2007, against the
Charlotte Bobcats in Charlotte. The following game, on March 28 against the Indiana Pacers, Josh eclipsed his previous career-high by scoring 22 points on 11-for-13 shooting. He also posted his first
double-double by grabbing 10 rebounds. In late December 2007, Boone earned a spot in the starting lineup. He replaced
Jason Collins as the starting center and contributed immediately, putting up a double-double almost every night. During the month of January, Boone was the target of a "
Hack-a-Shaq" by
Golden State Warriors coach
Don Nelson, in which a player is intentionally fouled repeatedly to take advantage of his poor foul shooting. That season, Boone was second-worst in the NBA in free-throw percentage among players with at least one hundred attempts, at 45.6% Boone would see fewer minutes with the Nets, in part due to his free throw shooting. His accuracy at the line continued to deteriorate, as he hit 37.6% in 2008–09 and 32.8% in 2009–10. Only one player in the league with at least ten attempts had a lower percentage,
Andris Biedrins, who made four of twenty-five attempts.
Post-NBA After not being re-signed by the Nets, Boone signed to play with the
Zhejiang Golden Bulls of China, with whom he would play for parts of three seasons. On January 17, 2013, Boone was acquired by the
Iowa Energy of the
NBA D-League. On January 26, after he had played in only two games, it was announced that Boone would miss the rest of the 2012–13 season with a knee injury. In February 2014, Boone signed with the
San Miguel Beermen as an import for the
2014 PBA Commissioner's Cup. He left the next month after just 2 games. On March 22, 2014, Boone was re-acquired by the Iowa Energy. In September 2014, Boone signed with
Manama of the
Bahraini Premier League. He went on to help Manama win their 19th championship in May 2015. On September 9, 2015, Boone signed with
BC Kalev/Cramo of Estonia. On January 13, 2016, Boone signed with
BC Khimki of Russia. He was supposed to replace injured Paul Davis and Ruslan Pateev. On August 2, 2016, Boone signed with
Pınar Karşıyaka of Turkey for the 2016–17 season. On October 24, 2016, he parted ways with Karşıyaka after appearing in only one game. On December 24, 2016, Boone signed with
Melbourne United of the Australian
National Basketball League as an injury replacement player. On February 21, 2017, Boone signed with the
Hong Kong Eastern Long Lions of the
ASEAN Basketball League. He helped the Long Lions win the championship after they defeated the
Singapore Slingers in the ABL Finals. On April 28, 2017, Boone re-signed with Melbourne United for the
2017–18 NBL season. On August 14, 2018, he re-signed with United for the
2018–19 NBL season. On May 21, 2019, Boone signed with the
Illawarra Hawks for
2019–20 NBL season. On March 4, 2020, he has signed with Al Nasr of the
UAE National Basketball League. Boone signed with Al Riffa of the
Bahraini Premier League on August 9. In November 2021, it was announced Boone was on the roster of Canadian club
Edmonton Stingers to strengthen their team for their maiden
BCL Americas campaign in the
2021–22 season. ==Career statistics==