"We expect that he will continue to mature and develop and play an important role on our club next season."
Markstrom, 23, has played in 31 NHL regular-season games, all with Florida, posting a 10-19-2 record with a .906 save percentage.
In 23 games with the Panthers last season, he went 8-14-3, including making a career-high 44 saves on Mar. 2, in a 3-1 win over the New York Rangers.
The Gavle, Sweden native, was drafted by Florida in the second round (31st overall) of the 2008 NHL Entry Draft.