Canas, 26, is out of contract at Betis and joins the ever-growing Spanish contingent at the Premier League club.
He is a deep-lying midfielder and could start next season playing alongside Leon Britton with Swansea as yet unsure whether they will be able to sign Villarreal's Jonathan De Guzman on a permanent deal following a successful loan spell.
Canas came through the youth system at Betis and helped the Seville side record an impressive seventh-place finish in La Liga this season.
Meanwhile, Swansea chairman Huw Jenkins has taken the opportunity to deny reports in the media that he has fallen out with manager Michael Laudrup over the size of the transfer budget available this summer.
“Myself, the manager and our recruitment staff are all agreed on the quality of players we would like to sign to help us remain competitive in the Barclays Premier League," Jenkins said.
“We are continuing to work behind the scenes, in private wherever and whenever we can, to strengthen our squad. For that reason it’s disappointing that I have to respond to the speculation of unrest at the club after the fantastic season we have had.
“There are substantial funds available to strengthen our squad over the summer while we are also in the privileged position, because of the way we’ve managed our finances over the years, that we do not need to sell anyone to fund those new recruits.
“It goes without saying that some of our targets will sign for other clubs for different reasons. But that’s the same for every club. The important thing, and a factor that has always been vitally important for us, is that we sign players who want to play for Swansea City for footballing reasons. If not, then we move on to the next target.
“It is true that I have not sat down with our manager since the last game of the season against Fulham, but that’s because we have both been away on holidays at different times. It doesn’t mean we haven’t spoken because I’ve had numerous conversations with Michael over the phone and there's been no difference of opinion on our original transfer targets."
- Sports & Recreation
- Jonathan De Guzman
- Michael Laudrup
- La Liga
- Leon Britton
- Huw Jenkins