The 31-year-old all-star center sustained a non-displaced fracture in his right hand, team doctors said.
Lecavalier's injury could serve to dampen the momentum of the Bolts' current late-season playoff push. The squad entered Tuesday six points behind Toronto and Winnipeg for the eighth spot in the Eastern Conference.
"Obviously it's real disappointing," Lecavalier was quoted as saying on the team's Web site. "This is the part of the year here where we are making a push and we're playing well, so it's too bad I can't help the team."
The Lightning's captain was injured during Saturday's 2-1 win over Washington, although he played the entire game.
Lecavalier left Monday's practice early and a subsequent magnetic resonance imaging exam revealed the break.
He has racked up has 21 goals and 25 assists over 58 games this season.