The 28-year-old played a key role in Atletico's shock La Liga success last term, scoring 10 goals from 34 appearances.
And his form did not go unnoticed, with the midfielder selected in his first Spain squad on Friday.
Garcia and Paco Alcacer, Mikel San Jose and Kiko Casilla - all uncapped - headlined Vicente del Bosque's new squad as they prepare to begin their Euro 2016 qualifying campaign next month.
"I'm sure that, just as the [Atletico] team has been evolving, he has also developed," Simeone said of Garcia.
"And with hard work, passion and quality - he's earned a place with the national side.
"He has an advantage because he can be fielded in a number of different positions and that is always positive.
"His call-up for the national team has come at a high point for him in his career."
Garcia and his Atletico team-mates face Eibar in La Liga on Saturday.
