After being selected in the first round by the New Jersey Devils in the 1992 Entry Draft, Jason Smith carried on a great junior career, winning several accolades. As a Regina Pats, he was named to the WHL's all-rookie team in 1992 and first all-star team in 1993. He was also named the league's outstanding defenceman, winning the Bill Hunter Trophy the same year as the captain of the team. Smith was also a member of the gold medal-winning Team Canada at the World Junior Championships in 1993
Smith made his NHL debut with the Devils in the 1993-94 season while also playing for the AHL's Albany River Rats. He missed the majority of the next season because of a knee injury but came back to captain the River Rats to a Calder Cup championship in 1995, the year the Devils took home Lord Stanley. Smith then moved up to the NHL for good, playing with the Devils until 1997 when he was dealt to the Maple Leafs.
After a few years in Toronto, Smith was traded to the Oilers in 1999 and settled in to his new club, becoming the captain for the 2001-02 season after Doug Weight was traded to the St. Louis Blues. Smith followed in the captaincy footsteps of such Oiler greats as Wayne Gretzky, Mark Messier, and Kevin Lowe.
The 2003-04 season marked Smith's fifth with the Oilers. Known more for his gritty play, Smith surpassed the 700-games played plateau in 2003-04 and continues to be one of the teams leaders both on and off the ice.
Following a year away from NHL hockey due to the lock out year, Smith would lead a surprising Oiler team as captain into the NHL Stanley Cup Finals in 2006. However, after a grueling seven game series the Edmonton Oilers would finish one win shy of the Stanley Cup after being defeated by the Carolina Hurricanes.
In 2006-07, the Oilers struggled and failed to qualify for the playoffs. During the off-season the club began to rebuild and dealt Captain Jason Smith and Joffrey Lupul to the Philadelphia Flyers in exchange for Joni Pitkanen and forward Geoff Sanderson. In his first and only season in Philadelphia, Smith Captained a rebuilt Flyers squad to an Eastern Conference showdown against their inter-state rivals from Pittsburgh. Despite the fact that the Penguins won the series, the Flyers' turnaround from the worst team in the league to their status in 2007-08 was a credit to Smith's leadership abilities.
On July 8th 2008, Jason Smith signed a two year contract with the Ottawa Senators worth $2.6 million US per season.
Aside from his World Junior experience, Smith has gone on to represent his homeland at 2001 World Championships.