Martínez scored in the 112th minute to secure Argentina’s third consecutive tournament victory (2021 Copa America, 2022 World Cup, 2024 Copa America).
Martínez, the tournament’s top scorer with five goals, blasted a shot past Colombia’s goalkeeper Camilo Vargas on a breakaway following a turnover.
Argentina clinched the title without their inspirational captain Lionel Messi, who was subbed out in the 66th minute due to an ankle injury.
The victory ended Colombia’s 28-game international win streak, which had dated back to February 2022, also against Argentina.
Colombia played without defender Daniel Muñoz, who was sent off after receiving a second yellow card during an altercation in the first half of their semifinal match against Uruguay on Wednesday night.