The Argentine central defender was a target for Manchester United this summer before David Moyes took over as boss.
However, with Rio Ferdinand's concerning lack of form and Nemanja Vidic's injury problems, there were some suggestions that Moyes could go back in for him.
"I have learned a lot since I came to Benfica and I am very happy at the club," Garay said in an interview with Benfica TV.
After establishing himself as a regular in the Argentine starting line-up, Garay hopes to feature in next year's World Cup in Brazil.
"We qualified and it will be my first World Cup if I get called up so I'm really excited," he added.