He played for the Washington Capitals twice, Dallas Stars, Tampa Bay Lightning, Los Angeles Kings, New York Rangers, Montreal Canadiens, and Phoenix Coyotes.

[3] In order to pursue his dreams as a hockey player, Halpern transferred to and later graduated from St. Paul's School in Concord, New Hampshire where he was roommates with future The Bachelorette winner Ian McKee.

There, he played four seasons of varsity hockey for the Princeton Tigers men's ice hockey team, was named an ECAC second team All-Star in 1998 and 1999, and in 1999 he scored 22 goals to tie for the most goals in the ECAC and was co-winner of Princeton's Roper Trophy for athletic and academic achievement.

On July 5, 2006, Halpern left the Capitals as a free agent and signed a four-year deal with the Dallas Stars.

On February 26, 2008, Halpern was dealt to the Tampa Bay Lightning along with Mike Smith, Jussi Jokinen, and a 2009 4th-round draft pick in exchange for Brad Richards and Johan Holmqvist.

Playing in a 5–4 loss in the opening round against the Canadian team on May 6, 2008, he suffered a ruptured anterior cruciate ligament and was expected to be out of action for 6–8 months.

[7] Halpern was traded from the Lightning to the Los Angeles Kings March 3, 2010, in exchange for Teddy Purcell and a 3rd round draft pick in 2010.

[9] In 30 games with the Rangers as a checking line forward, Halpern produced one assist before he was claimed off waivers to return to the Montreal Canadiens on March 23, 2013.

[12] On September 16, 2013, Halpern signed a one-year contract with Finnish Elite League team TPS, and was expected to make his SM-liiga debut in October.

[18] On June 22, 2018, the Tampa Bay Lightning named Halpern as assistant coach after parting ways with Rick Bowness.