Canas will become the fifth member of Swansea’s Spanish contingent, joining Pablo Hernandez, Michu, Angel Rangel and Chico Flores, with whom he shares an agent.
He told the Daily Mail: "I knew them all from playing against them in Spain. I know Chico the best as we are both from Cadiz and have been playing against each other since we were kids.
"I spoke to Chico and he said he has enjoyed the season at Swansea very much so I am pretty excited to join them all.
"Swansea have become very famous in Spain. Actually, together with Wigan, it is the most followed premier league club in Spain.
"Matches are always on TV and press coverage is quite big in Spain about the club and its Spanish footballers."