Costa converted from a Brazil international to la Roja earlier this season and had a stunning season with Atletico Madrid, starring as the club won La Liga. However, the 25-year-old has been a major fitness worry throughout the last few weeks, with a recurring hamstring problem limiting his participation in the final league match and the Champions League final.
While Costa has been picked to help Spain defend its crown in South America this summer, Juventus forward Fernando Llorente and Manchester City striker Alvaro Negredo miss out.
PHOTOS: USA vs. Azerbaijan | World Cup teams
Fernando Torres might not have had the best campaign at Chelsea but his performance against Bolivia on Friday may have helped sway Del Bosque as he will be part of the 23-man squad.
Atletico Madrid midfielder Koke, linked with Barcelona, is one of the relatively new faces in the Spain ranks, supported by veterans like Xavi, Andres Iniesta, David Villa and Gerard Pique.
Manchester City's Jesus Navas will be disappointed to have been considered disposable, though the likes of Juanfran Torres and Cesar Azpilicueta will be delighted be available to Spain.
Spain faces Netherlands, Chile and Australia as the team bids to defend the World Cup title it won four years ago in South Africa.
Goalkeepers: Iker Casillas, Pepe Reina, David de Gea
Defenders: Sergio Ramos, Gerard Pique, Raul Albiol, Javi Martinez, Jordi Alba, Cesar Azpilicueta, Juanfran Torres
Midfielders: Koke, Xavi, Xabi Alonso, Andres Iniesta, Sergio Busquets, Cesc Fabregas, Santi Cazorla, Pedro Rodriguez, Juan Mata, David Silva
Strikers: Fernando Torres, David Villa, Diego Costa