Sporting Lisbon were crowned Portuguese champions for the first time since 2002 after a 1-0 win over Boavista.
Paulinho scored the only goal of the game for the hosts, who remain unbeaten and are eight points clear of Porto with two games to play.
The result also marks the end of Porto and Benfica's 19-year hold on the Primeira Liga title.
Thousands of celebrating fans had greeted Ruben Amorim's side outside the Jose Alvalade Stadium before kick-off.
Sporting, who are captained by former Liverpool and Sunderland defender Sebastian Coates, went top of the table at the start of November and have remained there ever since.
It caps the end of a superb season for Amorim's team, who won the League Cup in January and comes just three years after a group of supporters attacked players and staff at the club's training base.
The incident led to the departure of coach Jorge Jesus, several senior members of the squad and club president Bruno de Carvalho.
- Snowfall is back: Hard-hitting drama about the crack epidemic in 1980s LA streaming now
- How Gen Z is learning to adapt and thrive: Young entrepreneurs find new ways to make money in Covid times