"Viktor has proven himself not only this year in the NHL, but the previous two seasons as the top goaltender in Sweden," Ducks General Manager Bob Murray said.
"We are pleased to be able to keep him and feel fortunate to have two top NHL goaltenders going forward."
Fasth, 30, is 8-0-0 with a 1.78 goals-against average and a .933 save percentage in his first NHL season. He needs one more victory to tie Ray Emery's record of nine consecutive wins to start an NHL career.
Fasth signed a one-year contract in May to be Jonas Hiller's backup after leading the Swedish Elite League the past two seasons.