The 39-year-old Argentina captain said the decision was painful but necessary, explaining that he felt the time had come to step away and allow a new generation of players to take their place.
Messi leaves the national team as Argentina's most-capped player and all-time leading scorer, having scored 125 goals in 207 appearances. During his remarkable international career, he led Argentina to World Cup glory in Qatar in 2022 and also won two Copa America titles.
In his farewell message, Messi said he had given everything he could to the national team and felt he had nothing left to offer.
He described his departure as a chapter that was deeply painful to close, saying he had always loved representing Argentina and would continue to do so in spirit. Messi also acknowledged the talented young players coming through the ranks, saying they deserved the opportunity to represent the country.
The football icon revealed that he wrote his retirement message on 21 July, two days after Argentina's defeat to Spain in this summer's World Cup final. Earlier in August, Messi had spoken about reconsidering his future in football following the death of his father, Jorge, who died aged 68 after a long illness.
Despite retiring from international football, Messi will continue playing at club level with Major League Soccer side Inter Miami.
His journey with Argentina began dramatically in 2005 when he came on as a substitute during a friendly against Hungary. Less than a minute after entering the pitch, he was sent off after his elbow struck defender Vilmos Vanczak.
However, that difficult beginning did little to define what followed. Messi went on to become one of football's greatest players, collecting some of the sport's biggest honours with Argentina.
He finishes as the second-highest scorer in World Cup history with 21 goals, behind France's Kylian Mbappe, and remains second on the list of international goalscorers behind Portugal's Cristiano Ronaldo.
Messi had previously retired from international football in 2016 after Argentina lost the Copa America final to Chile, but later reversed his decision. His return eventually led to some of the greatest moments in Argentina's football history.
Thanking supporters for their love over the past two decades, Messi said he would now support Argentina from the sidelines with pride.
