Messi, 34, dropped to the ground in joy at the full-time whistle and was swiftly mobbed by his team-mates, before being hurled in the air in celebration, as he finally claimed top-level honours with his country in his 10th major tournament, reports the BBC.
He also helped end Argentina’s 28-year spell since they last won the competition and was named player of the tournament after his four goals in the competition.
Angel di Maria proved the matchwinner with his superb lob, after taking down Rodrigo de Paul’s lofted pass.
Defending champions Brazil were disappointing, with their only chances of note coming when Richarlison and Gabriel Barbosa forced saves from Emi Martinez.
In a contrast of emotions, Messi’s opposite number 10 and former Barcelona team-mate Neymar sank to his knees in tears at the final whistle, as his own personal pursuit of international success continues, having missed Brazil’s 2019 Copa win through injury.
The pair, who played together at the Nou Camp between 2013 and 2017 before the Brazilian’s move to Paris St-Germain, embraced in a long-lasting hug while they waited for the trophy ceremony.
The game was watched by a small crowd of 7,000 invited guests, because of Covid-19 restrictions, but was the first of the tournament to have spectators in attendance.
The sparse home supporters made their voices heard, though, particularly every time Messi touched the ball, booing and jeering the forward.
The tournament, delayed by a year because of the coronavirus pandemic and moved from initial co-hosts Colombia and Argentina, was switched to 2019 hosts Brazil in a last-minute decision which received criticism in light of a surge in coronavirus cases in the country.