Manager Lionel Scaloni has named the 18-year-old in his first squad since winning the World Cup in Qatar in December for games against Panama and Curaco later this month.
Garnacho has scored five goals in 30 appearances across all competitions this season and is increasingly becoming a fixture in Erik ten Hag’s first-team at Old Trafford.
Born in Madrid, Garnacho is eligible to represent Argentina through his mother and joins a raft of big names in the squad.
Lionel Messi, who had been tipped to retire following the World Cup, returns alongside veterans Angel Di Maria and Nicolas Otamendi.
Argentina squad in full: Goalkeepers: Armani (River), Rulli (Ajax), E. Martinez (Aston Villa),
Defenders: Foyth (Villarreal), Montiel (Sevilla), Molina (Atletico Madrid), Perez (Udinese), Pezzella (Real Betis), Romero (Tottenham Hotspur), Otamendi (Benfica), L. Martinez (Manchester United), Tagliafico (Lyon), Acuna (Sevilla), Blanco (Elche),
Midfielders: Paredes (Juventus), Rodriguez (Real Betis), Fernandez (Chelsea), Perrone (Manchester City), Palacios (Bayer Leverkusen), De Paul (Atletico Madrid), Buonanotte (Brighton and Hove Albion), Almada (Atlanta United), Lo Celso (Villarreal), Mac Allister (Brighton and Hove Albion),
Forwards: Di Maria (Juventus), Correa (Atletico Madrid), Buendia (Aston Villa), Carboni (Inter Milan), Messi (PSG), Dybala (Roma), L. Martinez (Inter Milan), Alvarez (Manchester City), Garnacho (Manchester United), Gonzalez (Fiorentina), Gomez (Sevilla).