The 21-year-old reigning Major League Soccer Newcomer of the Year is a late replacement for the roster spot previously occupied by Joaquín Correa.
The move makes Almada the first active Atlanta Untied player to play in a FIFA World Cup and the first Argentine from MLS to do so.
The Argentina Football Association made the announcement officially on Thursday.
"First and foremost, we couldn’t be happier for Thiago to have the opportunity to represent Argentina at the FIFA World Cup," Atlanta United Vice President and Technical Director Carlos Bocanegra said in a press release from the club. "He’s consistently shown his quality and has proven to be a top player deserving of this call-up. This is a proud moment for the club and we’re confident he’ll represent both Atlanta United and Major League Soccer with world-class skill on the game’s biggest stage."
Almada scored six goals and recorded a team-high 12 assist for Atlanta United in his debut MLS season. He signed with Atlanta United as one of the team's Designated Players in Feb. 2022.
Argentina kicks off Group C play against Saudi Arabia on Tuesday. Group C includes Argentina, Saudi Arabia, Mexico and Poland.