At 38, Messi had not confirmed his participation in what will mark his sixth World Cup, a historic milestone for the Argentine star.
However, it was largely expected that the eight-time Ballon d’Or winner would return to captivate fans, four years after securing the trophy in Qatar.
In addition to confirming Messi’s inclusion, Thursday’s announcement notably omitted Real Madrid’s Franco Mastantuono from the Argentina lineup.
The 18-year-old Mastantuono is hailed as one of the standout prospects in Argentine football.
The largest World Cup ever, jointly hosted by the United States, Canada, and Mexico, begins on June 11.
Argentina’s opening match is set for five days later against Algeria in Kansas City.
Messi has faced an injury scare recently, with his club Inter Miami revealing this week that medical tests showed he has muscle fatigue in his left hamstring.
The Major League Soccer team did not provide a specific timeline for Messi’s return after he exited abruptly in the 73rd minute during Miami’s 6-4 win over Philadelphia on Sunday.
Nonetheless, Scaloni has downplayed the seriousness of the injury.
Romero returns
Center-back Cristian Romero, who sustained a knee injury last month and has not played since, has also been included in the squad.
The Tottenham Hotspur captain was sidelined for the rest of the Premier League season after a collision with Sunderland striker Brian Brobbey into his own goalkeeper.
Argentina’s lineup features 17 of the 26 players who won the title in Qatar.
Young talents called up include 21-year-olds Nicolas Paz and Valentin Barco.
Palmeiras forward Jose Manuel Lopez, who made his international debut only last year, also makes the roster.
Other significant absences include Emiliano Buendia, who is in great form at Aston Villa, and Roma’s Paulo Dybala.
The South American powerhouses will travel to the United States for pre-World Cup friendlies against Honduras on June 6 and Iceland on June 9.
Argentina’s World Cup group also includes Austria and Jordan.
In addition to Messi, Portuguese forward Cristiano Ronaldo and Mexican goalkeeper Guillermo Ochoa are also anticipated to make their sixth World Cup appearances this summer.
Squad:Goalkeepers: Emiliano Martinez (Aston Villa, ENG), Geronimo Rulli (Marseille, FRA), Juan Musso (Atletico Madrid, ESP)
Defenders: Gonzalo Montiel (River Plate, ARG), Nahuel Molina (Atletico Madrid, ESP), Lisandro Martinez (Manchester United, ENG), Nicolas Otamendi (Benfica, POR), Leonardo Balerdi (Olympique Marseille, FRA), Cristian Romero (Tottenham Hotspur, ENG), Facundo Medina (Marseille, FRA), Nicolas Tagliafico (Lyon, FRA).
Midfielders: Leandro Paredes (Boca Juniors, ARG), Rodrigo de Paul (Inter Miami, USA), Exequiel Palacios (Bayer Leverkusen, GER), Enzo Fernandez (Chelsea, ENG), Alexis MacAllister (Liverpool, ENG), Giovani Lo Celso (Real Betis, ESP), Valentin Barco (Strasbourg).
Attackers: Lionel Messi (Inter Miami, USA), Nicolas Paz (Como, ITA), Thiago Almada (Atletico Madrid, ESP), Nicolas Gonzalez (Atletico Madrid, ESP), Julian Alvarez (Atletico Madrid, ESP), Giuliano Simeone (Atletico Madrid, ESP), Lautaro Martinez (Inter Milan, ITA), Jose Manuel Lopez (Palmeiras, BRA).
