The move came after Saturday's 5-3 loss to the Senators in Ottawa.
"Guy has poured his heart and soul into the Lightning organization for these past three years and we appreciate all the work he has done," Lightning vice president and general manager Steve Yzerman said in a release. "But ultimately I am not satisfied with the direction we are heading and I believe making a change today is in the best interest of our franchise.”
Tampa Bay (13-17-1) is 14th in the Eastern Conference and sit five points out of a playoff spot.
Assistant coaches Martin Raymond and Dan Lacroix will share coaching duties for Tampa Bay's game in Winnipeg against the Jets on Sunday.
Boucher's hiring in 2010 was Yzerman's first major move as a Lightning executive, and it seemed to pay off in the short-term as Boucher led the team to the Eastern Conference Final in his first season behind the bench.
It was also his first year as an NHL coach, having moved from his post with the Hamilton Bulldogs of the AHL shortly after he won that league's coach of the year award.
Prior to coaching the Bulldogs, Boucher served for three seasons as the coach of the Drummondville Voltigeurs in the Quebec Major Junior Hockey League, culminating in a 54-win season and Memorial Cup appearance in 2009.