Grêmio arrived in Argentina off a 1-0 win in the first leg of the final in Porto Alegre, and bolstered their advantage with first-half goals from Fernandinho and Luan.
Fernandinho’s blistering left-footed shot put the visitors up 1-0 in the 27th minute. Luan floated a shot over Lanús goalkeeper Esteban Andrada in the 42nd minute to double the advantage and cap a Copa that saw him named the best player of the 2017 edition of the South American club competition.
Although Lanús had produced four second-half goals against River Plate in the return leg of the semifinals, there would be no miracle comeback this time.
José Sand converted a penalty in the 72nd minute to pull back one goal, but the Argentinian side were denied a first Copa Libertadores title.
Grêmio added their third title to those they won in 1983 and 1995.