The 22-year-old's previous deal was due to expire at the end of the season, but the west Londoners have moved to tie down the youngster's future as they scrap to remain in the Premier League.
|9/1||Fulham are 9/1 with bet365 to beat Sheffield United 2-1|
The Swede moved to Craven Cottage in 2010 as part of the deal that took Paul Konchesky from Fulham to Liverpool and has since impressed in the capital, making 49 appearances in all competitions.
His form has also led to international recognition, and he now boasts 16 caps for Sweden having made his debut in a friendly against Brazil in 2012.
Fulham manager Rene Meulensteen, meanwhile, has confirmed that the Cottagers have made a move to sign Leicester City defender Liam Moore.
“We've put a bid in, but it's up to (Fulham chief executive) Alistair Mackintosh,” said the Dutchman. “(Reports) are quite accurate, but Macintosh is dealing with transfers. I'm focused on training the players.”