The Dutch international was voted the player of the year in his debut season at the Liberty Stadium by both players and supporters.
Vorm told the club's official website that he is happy to finally confirm the deal.
He said: "I'm delighted, I'm enjoying my time here very much and it is one of the reasons why I've signed an extension.
"I can also only see things at Swansea getting better and better. I can see a lot of positive things happening here and I believe the club has a bright future ahead of it.
"The club has signed a lot of its quality players for longer periods, which is a good thing."
The 28-year-old joined the Swans from FC Urecht last summer and had less than two years to run on his original contract before signing the deal on Thursday.