Vazquez was part of the Spanish Under-21 side that won this year's European Championships, scoring one goal in his only appearance in the tournament.
The 22-year-old striker's loan move is understood to include a view to a permanent transfer at the end of the season, and Swansea chairman Huw Jenkins believes that the player has shown plenty of potential.
"He is a young player with plenty of potential. He has already done well out in Spain and looks like the right signing for us at this stage," Jenkins told the club's official website.
Vazquez made 89 appearances for Espanyol and Getafe in La Liga, scoring 14 goals.