Benfica has won its fifth Portuguese league title in six seasons after routing Santa Clara 4-1 on Saturday.
Benfica lifted its 37th league trophy by finishing two points ahead of defending champion Porto, which defeated Sporting Lisbon 2-1.
Benfica trailed Porto by seven points in January. It won four straight titles before Porto ended its streak last year.
A draw would have been enough for Benfica at the Stadium of Light, as it entered the final round with a better head-to-head tiebreaker over its rival.
The host got off to a fast start and was up 3-0 by halftime with goals by Haris Seferovic, Joao Felix, and Rafa Silva. Seferovic scored again early in the second half before Santa Clara got its lone goal through Cesar.
Porto struggled at home against third-placed Sporting, which played with 10 men from the 19th minute because of a red card to defender Cristian Alexis Borja.
Danilo Pereira and Hector Herrera scored late in the second half after the visitors opened the spell with a Luiz Phellype goal.
Sporting qualified for the Europa League along with fourth-placed Braga.
Porto will play in the qualifying rounds of the Champions League, while Benfica goes straight into the group stage.
Chaves, Nacional and Feirense were relegated.