Coburn has spent the last five campaigns with the Lightning and contributed 23 points in 74 games during 2018-19, his highest total since joining the team.
The 34-year-old also averaged 16:07 of ice time while recording 62 blocks and 96 hits this past season. Additionally, he posted the second-highest possession rating at five-on-five among Lightning defensemen with a Corsi For of 52.75 (minimum 20 games played).
The Lightning now have $76.1 million committed to 18 players for next season, leaving $6.87 million in projected cap space, according to CapFriendly.
Tampa Bay still has four restricted free agents in line for new deals, including 41-goal-scorer Brayden Point. Veteran defensemen Dan Girardi and Anton Stralman are also set to become unrestricted free agents on July 1.