As a youth, Reasoner played in the 1990 and 1991
Quebec International Pee-Wee Hockey Tournaments with a
minor ice hockey team from
Rochester, New York. Reasoner was selected in the first round of the
1996 NHL entry draft, 14th overall, by the
St. Louis Blues. This followed two years of high school hockey at
McQuaid Jesuit High School, two years of high school at
Deerfield Academy in Massachusetts and three years at
Boston College (BC), where he was named Rookie of the Year his freshman year, and named All-American his junior season when he led the
Eagles ice hockey team to the NCAA finals. He skated alongside BC legend
Brian Gionta. Reasoner split 1998–2001 between the Blues and their top minor league affiliate, the
Worcester IceCats of the
American Hockey League (AHL). In 2003, he was voted a starter on the IceCats' tenth-anniversary All-Time Team. On July 1, 2001, Reasoner (along with
Jochen Hecht and Jan Horacek) was traded to the
Edmonton Oilers in exchange for Oilers' captain
Doug Weight and Michel Riesen. In November 2003, Reasoner suffered a severe knee injury when he crashed into the end boards. During the
2004–05 NHL lockout, Reasoner played 11 games for
EC Red Bull Salzburg of the Austrian League. On August 9, 2005, Reasoner signed a one-year contract extension with the Oilers. On March 9, 2006, Reasoner (along with
Yan Stastny and a second-round pick in the
2006 NHL entry draft (used to select
Milan Lucic)) was traded to the
Boston Bruins in exchange for
Sergei Samsonov. On July 4, 2006, as a free agent, Reasoner signed a two-year contract to return to the Edmonton Oilers. After the expiry of his deal, on July 17, 2008, Reasoner signed a contract with the
Atlanta Thrashers. On June 24, 2010, Reasoner (along with the Thrashers' first- (24th overall) and second-round picks in the
2010 NHL entry draft (used to select
Joey Crabb and
Jeremy Morin respectively)) was traded to the
Chicago Blackhawks in exchange for
Dustin Byfuglien,
Ben Eager,
Brent Sopel and
Akim Aliu. One month later, on July 22, 2010, due to salary cap restrictions within the Blackhawks' organization, Reasoner was traded to the
Florida Panthers in exchange for center
Jeff Taffe. After the Panthers traded away captain
Bryan McCabe, Reasoner was named an assistant captain. On July 1, 2011, Reasoner signed a two-year contract with the
New York Islanders. ==Career statistics==