The Tampa Bay Times reported the contract will pay Killorn $2.4 million for 2014-15 and $2.7 million for 2015-16. Killorn, 24, was scheduled to become a restricted free agent July 1.
"They wanted me to be part of what they have going on in the future, so I was excited about that," Killorn told the Times.
Killorn had 17 goals and 41 points in 82 regular-season games for the Lightning in 2013-14. He ranked sixth on the team in goals in his first full season in the NHL. He also had a goal and two points in four Stanley Cup Playoff games.
The 6-foot-1, 200-pound left-shot forward has 24 goals, 60 points and 77 penalty minutes in 120 career games with the Lightning. Tampa Bay selected him in the third round (No. 77) of the 2007 NHL Draft.