The 34-year-old Smithson was acquired by the Cats from the Nashville Predators last season for a sixth-round pick.
In 35 games with the Panthers this season, Smithson tallied two goals and added three assists, while posting a -4 rating. He picked up one assist in 16 games with Florida last season.
The veteran pivot will add depth and the ability to win faceoffs to a young Edmonton team looking to slip into the playoffs.
For a less than thrilled look at the trade, check out Copper & Blue's take on the deal.