On June 26, 2008, Giddens was selected by the
Boston Celtics with the 30th overall pick in the
2008 NBA draft. He had worked out with the Celtics for three days, and received praises from head coach
Doc Rivers, who thought he could fight for minutes on the team right away. He was even mentioned as a possible replacement for
restricted free agent Tony Allen. Giddens was already familiar with
Leon Powe and
Kendrick Perkins, who were his teammates at the 2003
McDonald's All-American Game. But on behalf of his agent Aaron Mintz, Giddens declined to work out at the Celtics' minicamp in early July, because he had not signed a contract yet. On November 15, 2008, Giddens was assigned to the Boston Celtics'
NBA Development League affiliate team, the
Utah Flash. He had played with the Celtics in the
2008–09 pre-season but had been on the inactive list for the first 10 games of the regular season. Giddens started his first game for the Boston Celtics on January 2, 2010. On February 18, 2010, Giddens,
Bill Walker and
Eddie House were traded to the
New York Knicks for
Nate Robinson and
Marcus Landry. On October 13, 2010, Giddens's agent said that Giddens would spend the 2010–11 season with
Asseco Prokom Gdynia in
Poland, but Giddens left the team in December 2010 by mutual consent. In September 2011, Giddens signed with
PAOK Thessaloniki of Greece. In September 2012, Giddens signed with
Basket Brescia Leonessa, an Italian Legadue team. On June 30, 2014, he signed with
Vaqueros de Bayamón of Puerto Rico. On November 22, 2014, Giddens signed with
Peñarol de Mar del Plata of Argentina. On March 10, 2015, he was waived by the Peñarol after appearing in seventeen
LNB games. In January 2017, Giddens signed with
Club Trouville of the
Liga Uruguaya de Basketball. The next month, he left the club after appearing in five games. On February 22, 2017, he signed with Mexican club Mineros de Parral. On March 22, 2018, Giddens signed with
Ferro Carril Oeste of the
Liga Nacional de Básquet in
Argentina. ==Stabbing incident==