Witkowski, 6-foot-2, 200 pounds, appeared in four games with the Lightning in 2015-16. He also made his Stanley Cup Playoff debut, skating in two games during the second round against the New York Islanders. Witkowski also played in 70 games with the Syracuse Crunch of the American Hockey League, recording three goals and 14 points. He ranked third on the team for games played and led all blue-liners for plus/minus with a plus-2 rating.

A native of Holland, Michigan, Witkowski has played in 20 career NHL games, all with the Lightning, during the previous two seasons, registering 19 penalty minutes. He has also amassed 199 career AHL games, all with Syracuse, with seven goals, 34 points and 465 penalty minutes. Witkowski has skated in three career Calder Cup Playoff games, all during the 2015 playoffs, and recorded an assist.

Witkowski was drafted in the sixth round, 160th overall, of the 2008 NHL Draft.