Vazquez, 22, has completed the move with a view to earning a permanent contract with Michael Laudrup's Premier League side.
The forward is a Spain international at youth level and was a member of the squad that won the UEFA Under-21 European Championship earlier this year.
"Vazquez is a young player I know from his time at Espanyol and now Getafe," Laudrup told the club's official website.
"He is a little different to the strikers we have and has the characteristics we have been looking for. He will give us a different option."
Swansea chairman Huw Jenkins was also pleased with the confirmation of the deal.
"He is a young player with plenty of potential," he said.
"He has already done well out in Spain and looks like the right signing for us at this stage."
Vazquez, who joined Getafe in 2012 from Espanyol, scored four goals in 29 matches last season.
