The new deal will keep the former Utrecht star at the Liberty Stadium until the summer of 2016.
"I'm delighted," Vorm said. "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 Premier League has been all I expected it would be - and better. When you play in front of our fans and witness the support they give you, it's fantastic.
"We know how much the club means to them. And I'm not just talking about the Liberty Stadium. They also travel in their thousands to away games. It makes every game in a Swans shirt enjoyable."