Rakell joined the Pennsylvania club from Anaheim this spring and accounted for 13 points in 19 regular season games.
Now the Swede is rewarded with a longer contract.
In total, Rakell has accounted for 352 points in 569 games in the NHL over ten seasons.
It is speculated that the extension with Rakell may reduce the chances that the Russian superstar Evgeni Malkin will stay in the Penguins.