The 21-year-old forward signed a US$37.5-million, five-year contract extension Tuesday, ending a set of negotiations that extend all the way back to last year.
"I am excited we were able to reach an agreement today," Stamkos said in a release. "This was obviously very important to me ... There is no place I'd rather be than as a member of the Tampa Bay Lightning."
Stamkos had been a restricted free agent since July 1 and there was much speculation he'd be the target of an offer sheet.
Even though he scored a major raise, the $7.5-million annual cap hit he'll carry is less than Alex Ovechkin ($9.53 million per year), Sidney Crosby and Evgeni Malkin ($8.7 million each) received in their second NHL deals.
Stamkos will receive $8 million each of the next four seasons and $5.5 million in 2015-16.
"Steven is extremely important to this franchise and is part of the foundation of our hockey team," said Lightning GM Steve Yzerman. "We are very pleased to have him signed and look forward to seeing him in a Lightning uniform for years to come."
Over the past two seasons, Stamkos scored a league-leading 96 goals. He had 51 of those goals in 2009-10, when he shared the Rocket Richard Trophy with Crosby.
The first overall pick in 2008 has 232 points (119-113) in 243 career games with the Lightning.