The Predators announced the trade Friday. The deal gives Nashville nine picks for the June draft in Pittsburgh.
Smithson, 33, scored the first overtime goal in Nashville postseason history last April in Game 5 of the Predators' Western Conference opening series with Anaheim. The Predators went on and won the series on home ice in six games.
A native of Vernon, B.C., he played 497 regular season games for Nashville, which ranked sixth in franchise history. He also ranks fifth with 31 postseason games played.