Jason Spezza was drafted second overall by the Ottawa Senators in the 2001 NHL Entry Draft after being named the Top CHL Prospect. He made his NHL debut in 2002–03 with Ottawa,  recording 21 points in 33 games.

In his first full season with the Senators, Jason scored 77 points in 78 NHL games.

Due to the NHL lockout in 2004-05, Spezza returned to the AHL’s Binghamton Senators where he scored 117 points and was named winner of the  John B. Sollenberger Trophy as the league’s leading scorer as well as the Les Cunningham Award as league MVP.

Spezza returned to the Ottawa Senators for the 2005-06 season where he was started on the first line with teammate Danny Heatley. With the addition of Daniel Alfredsson to the line, they became known as the “Cash” line and were one of the leagues most productive trios. Despite an injury shortened season, Spezza managed 90 points in 68 games.

Spezza signed a seven-year contract extension with the Senators worth $49 million on November 2, 2007. That year he finished first among all Senators in points (92) and assists (58) while ranking second in plus-minus (+26) and third in goals (34).

The following few years saw point totals decrease as he was plagued by injury as well as questionable defensive play. Trade rumours circulated throughout Ottawa but no trade materialized. Despite missing 22 games due to injury in the 2009–10 season, Jason still managed to score 23 goals and pick up 34 assists for 57 points in 60 games to finish second on the team in scoring.

Near the end of the 2011-12 season he was named alternate Captain of the Senators. In that same year he again led the Senators in scoring with 84 points, while ranking second in goals (34) and assists (50),  he matched a career high in registering the 34 goals.

Off the ice Jason married girlfriend Jennifer Snell on July 25, 2009 and have 2 children together. Jason participates in many charities outside of hockey including the “Spelling with Spezza” program. The program recognizes the importance of spelling. Spezza visits selected classes registered for the program. Last season over 600 classes in the Ottawa-Gatineau area participated in Spelling with Spezza. He is also involved in the Ronald McDonald House charity.