Smithson, 34, had two goals, five points and was ranked first on the Panthers with a 54 percent faceoff winning percentage. He won 199 of 363 draws this season.
"Jerred is well known for his defensive abilities and is a very strong faceoff person," Oilers general manager Steve Tambellini told the team's website. "He brings us size and some strength in that faceoff circle. He can play wing and center. The fact that he's a veteran player is something that we've been looking for."
Smithson (6-foot-3, 209 pounds) is in his 10th NHL season. He played for the Los Angeles Kings and Nashville Predators before joining the Panthers last season. In 577 career NHL games, Smithson has 38 goals and 95 points.
"This was a move of, No. 1: veteran experience. And No. 2: Acquiring a versatile centreman, and we need help in faceoffs," Tambellini said. "There are going to be critical situations down the stretch where we'll need that. ... The more you can retain the puck, the better."
Smithson joined the Panthers on Feb. 24, 2012, in a trade with the Predators in exchange for a 2012 sixth-round pick.
"He went to the playoffs I'm pretty sure with Nashville once or twice so he's been there before and we can use him down the stretch when we need a little bit of that leadership," Oilers forward Ryan Jones said. "We don't have too many guys in this locker room that have experienced a push to the playoffs, so anytime you can add a little bit of that it'll help for sure."