Landeskog was the second overall selection in the 2011 NHL draft and he won the 2011-12 Calder Memorial Trophy as the league's top rookie.
"Gabe is and will continue to be a large part of the foundation of this hockey team for many years to come," Avalanche executive vice president of hockey operations Joe Sakic said in a statement announcing the deal.
"Signing our captain to a long-term extension demonstrates the commitment of Stan and Josh Kroenke to this franchise and to our fan base. In just two seasons, Gabe has already proven to be a great asset to our organization both on and off the ice. The fact that he has agreed to a long-term deal shows that he believes in this team, his teammates and the direction of this franchise moving forward."
The left winger has collected 31 goals and 38 assists in 118 career games.
"I would like to thank the Kroenke family and the entire Avalanche organization for their trust and belief in me," Landeskog said in the statement. "I love Colorado and I love being a part of this wonderful community. There is no other place I'd rather be than in Denver wearing the Avalanche logo. I am looking forward to training camp and the upcoming season."
After last season, he helped Sweden capture the gold medal at the 2013 IIHF World Championship in Stockholm and Helsinki.
Information from The Associated Press was used in this report.