The star centre, who turns 20 on Aug. 7, became the NHL's youngest MVP since Wayne Gretzky when he was awarded the Hart Trophy last month after winning the scoring title with 120 points. He also won the Pearson Award as most outstanding player in a poll of NHL Players' Association members.
The extension averages out to $9 million a season, but Crosby and agent Pat Brisson are believed to have settled for less than the maximum they could have demanded from the Penguins.
"I really enjoy playing and living in Pittsburgh and I want to be here for a long time," said Crosby. "Individual honours and scoring championships are great, but my No. 1 goal is to win the Stanley Cup.
"I'd love to be a part of bringing the Cup back here to Pittsburgh."
The native of Cole Harbour, N.S., was already under contract for next season for a base salary of $850,000 to complete his initial three-year, entry-level deal.
"Sidney has proven himself to be a dynamic player and team leader at a very young age, and it is exciting news for our franchise and our fans to have him under contract for the next six seasons," GM Ray Shero said in a release on Tuesday. "When you've got a guy who leads the league in scoring and wins the MVP award at the age of 19, you know you have someone very special."
Crosby is the youngest player in NHL history to record 100 and 200 career points. He was named captain of the Penguins last May, becoming the youngest team captain in NHL history.
Pittsburgh won 25 more games last season than they had a year earlier and finished with 47 more points. The Penguins were eliminated in the first playoff round by eventual Stanley Cup finalist Ottawa.
Crosby made his NHL debut in October 2005 after being the No. 1 entry draft selection. He scored 39 goals and assisted on 63 in his rookie season. Last season, he became the youngest player ever to win the Art Ross Trophy when he led the league in scoring with 36 goals and 84 assists.
The signing of the five-foot-11, 194-pound centre is the latest big-money deal that follows the recent increase in the league salary cap to just over $50 million from last season's $44 million.
The New York Rangers will pay Scott Gomez $10 million next season after signing the unrestricted free agent and former New Jersey Devils forward to a $51.5-million, seven-year contract.
The Philadelphia Flyers signed free-agent Daniel Briere to a $52-million, eight-year contract. It's also front-loaded and will pay Briere $10 million next season.
The Buffalo Sabres will pay Thomas Vanek $10 million next season after retaining the forward in a $50-million, seven-year pact that matched an offer sheet from the Edmonton Oilers.
Jaromir Jagr of the Rangers had a league-high salary of $8.36 million last season, and he's under contract for the same amount for the next two years.
Tampa Bay's Brad Richards got $7.8 million and Detroit's Nick Lidstrom, former Islander Alexei Yashin and Toronto's Mats Sundin each were paid $7.6 million last season. Boston's Zdeno Chara and New Jersey's Patrik Elias each got $7.5 million.