The 25-year-old, who scored twice in last season's League Cup final win over Bradford, had a year remaining on his previous deal but was delighted to agree a new contract which ties him to the Swans until July 2017.
Dyer told the club's official website: "I've been here four years now and I wanted to stay at Swansea.
"I didn't even think about going anywhere else, so it is nice to get it all sorted."
The former Southampton wide man, whose contribution to Swansea's Wembley triumph saw him land the Alan Hardaker Trophy for the man of the match, initially moved to south Wales on loan in 2009 and quickly became a first-team regular.
His form since the club secured promotion to the Premier League has won many plaudits and he was briefly touted as a possible England call-up.
Despite increased competition for places with the arrival of Pablo Hernandez last term, Dyer still made 44 appearances in all competitions as Swansea enjoyed the finest season in their 101-year history.
And with their Europa League campaign already under way - Swansea play Malmo in the second leg of their third-qualifying-round tie on Thursday - Dyer is looking forward to the next stage in the club's development.
"We've made a lot of progression here as a club, and I feel I have progressed too," he said.
"I am still trying to improve as a footballer and I feel I can do that here.
"I think the club can continue to improve. We have made some quality signings and the squad strength is very strong now.
"You look at the potential of the club when you are making key decisions like this, and I don't see the club going downhill in anyway. I can only see it going up and up."