The 33-year-old is coming off a 2017-18 season split between the Edmonton Oilers and Columbus Blue Jackets. He tallied eight goals and 19 points with Edmonton in 60 contests and another four points in 20 games with Columbus.
Letestu, who's traditionally played center, could face a tough challenge if he hopes to land a job at the position with the Panthers. Aleksander Barkov and Vincent Trocheck hold down the first two spots, so the veteran would likely have to edge out either Henrik Borgstrom or Derek MacKenzie for a bottom-six center job.
Letestu has amassed 93 goals and 210 points during 558 games across his nine-year NHL career.