Angel Di Maria scored the gamewinner with a crafty half-volley over Brazil keeper Ederson in the 22nd minute. Rodrigo de Paul set up Di Maria with a perfectly timed cross-field pass.
Lionel Messi, who has collected more than 30 titles with Barcelona, finally lifted a trophy with Argentina, which hadn't celebrated a championship since the 1993 Copa America.
Lionel Messi: Argentina finals
2005 U-20 World Cup: Argentina 2 Nigeria 1
2007 Copa America: Brazil 3 Argentina 0
2008 Olympics: Argentina 1 Nigeria 0
2014 World Cup: Germany 1 Argentina 0 (OT)
2015 Copa America: Chile 0 Argentina 0 (PKs, 4-1)
2016 Copa America Centenario: Chile 0 Argentina 0 (PKs, 4-2)
2021 Copa America: Argentina 1 Brazil 0
The 34-year-old Messi didn't play a major role in Argentina's 1-0 Copa America final win over Brazil, but he scored four goals and made five assists during La Albiceleste's run to the final.