Benfica avoided a slip-up against Santa Clara to secure their 37th Portuguese league title.
The Lisbon-based side needed only a point in their final match, with rivals Porto looking to take advantage of anything less.
However, two goals from Swiss forward Haris Seferovic, one from Joao Felix and Rafa Silva secured a 4-1 victory.
Porto recorded a 2-1 win over Sporting Lisbon in a game which saw both teams reduced to 10 men.
Sporting left-back Cristian Borja was shown a straight red in the 20th minute before forward Luiz Phellype gave the visitors the lead.
Danilo Pereira equalised in the 78th minute before Hector Herrera grabbed an 87th minute winner. Porto’s Jesus Corona received two yellows in stoppage time.
Benfica finished the season with 87 points, two ahead of Porto, who were last year’s champions, with Sporting third on 74 points.