Nicholas was selected in the 2003 USBL Draft by the Texas Rim Rockers (59th overall). He then moved to Italy for the 2003-04 season, signed by Fabriano Basket, in the Italian LegADue. He led Legadue in scoring with 27.1 points per game that season. He was signed for the 2004-05 season by Basket Livorno. He led the Lega in scoring with 22.8 points per game. At the end of the Italian regular season, he moved to Spain, signed for the remainder of the season by Saski Baskonia Vitoria. He then went back to Italy for the 2005-06 season, signed by Benetton Treviso. He led the Euroleague in scoring with 18.4 points per game. He moved to Turkey for the 2006-07 season, signed by Efes Pilsen. On June 24, 2008 he signed a 2-year contract with Greek club Panathinaikos. Nicholas helped Panathinaikos win the 2009 and 2011 Euroleague championships. He also won the Greek cup in 2009 as well as the Greek championship in 2009, 2010, and 2011. In July 2011 he signed with Armani Jeans Milano. In January, 2012 Nicholas was waived by Armani Jeans Milano.
In July, 2012 after being a free agent for 7 months since his departure from AJ Milano, Nicholas signed a one-year contract with the Russian club CSKA Moscow. However, on November 23, 2012, Nicholas has reached an agreement to terminate his contract with the team by mutual agreement. In July 2013 he announced retirement.
In February 2008, Nicholas refused to travel with Efes Pilsen for the away match against Partizan Belgrade in Belgrade, due to an advice for U.S. citizens not to visit Serbia related to the tension after the declaration of independence of Kosovo. He was then banned from the club and shortly after that he was released. In March 2008 he shortly negotiated with Israeli side Maccabi Tel Aviv on a three-year contract offer, but came to no final contract agreement with the club.