Newbury began his hockey career by playing in the Ontario Hockey Leaguewith the Belleville Bulls. Newbury played the 1998-99 and part of the 1999-00 seasons with the Bulls before being sent to the Sarnia Sting. Newbury would go on to play in four seasons with the Sting between 2000 and 2003, where he would compile a 104 point season in 2001-02, and a 92 point season in 2002-03. In his five seasons in the OHL, Newbury played in 306 games, scoring 122 goals and 184 assists for 306 points.
Newbury was selected 139th overall by the San Jose Sharks in the 2002 NHL Entry Draft. However, Newbury elected to remain with the OHL for another season, and did not come to a contract agreement with the Sharks. In October of 2003, Newbury signed with the Toronto Maple Leafs as a free agent, and was sent to the Maple Leaf's AHL affiliate, the St. John's Maple Leafs. Newbury played parts of three seasons with the St. John's Maple Leafs/Toronto Marlies franchise, until he was called up by the parent club during the 2006-07 season. Newbury made his NHL debut on December 23, 2006 against the Washington Capitals. Newbury scored his first NHL goal on January 1, 2007 against Boston Bruin's goaltender Tim Thomas. Newbury went on to play in 15 games for the Maple Leafs in 2006-07, recording 2 goals and four points. Newbury once again played for the NHL Maple Leafs in 2007-08, playing in 28 games and recording 1 goal and 2 points. Newbury was then returned to the AHL Marlies, where he continues as an active member of the affiliate's roster.