Bayern Munich celebrated in an almost empty stadium after securing their eighth consecutive title.
Robert Lewandowski eliminated Jerome Boateng's chipped pass to secure the winner for Werder Bremen – and seal the league with two games to spare.
Bayern's 11th consecutive Bundesliga victory put them 10 points ahead of Borussia Dortmund, who have three games left.
Bayern ended the game with 10 men after Alphonso Davies was sent off for two yellow card crimes.
Polish striker Lewandowski has scored 31 league goals this season, a figure equal to a foreign player's season record in the league. Pierre-Emerick Aubameyang, now at Arsenal, scored 31 Bundesliga goals for Borussia Dortmund in 2016-17.
Bayern were far from their best against a team from Werder Bremen, which was fighting for survival on the other side of the table.
With the goalless game, Bremen's Maximilian Eggestein came close enough before Lewandowski's quality winner, after Kingsley Coman narrowly headed.
Coman re-approached before teenager Davies was sent off in the remaining 11 minutes, while Werder Bremen had a late appeal for a declined handball penalty.
Bayern celebrate in unusual circumstances
With seven points ahead of Borussia Dortmund's closest rival, with three games to go, Bayern needed a victory in the remaining three games to win another title.
Hansi Flick's side did just that – but they crossed the line in unusual circumstances.
When Bayern won the title on the last day of last season, they did so after an emphatic 5-1 win over Eintracht Frankfurt in front of 75,000 fans at the Allianz Arena.
On Tuesday, there were no fans present at Weserstadion, with 42,000 capacity from Werder Bremen, when they finished the title in heavy rain.
The full-time whistle was greeted with cheers from Bayern players who echoed through the empty stadium, but it was a far cry from previous title celebrations before the coronavirus pandemic.
"The type of football we've played in the past few months is amazing," said Flick, the four-time Bundesliga winner with Bayern as a player.
"You could feel the passion, the joy of the game and the team spirit."
From a humiliating 5-1 defeat to champions
With home games in Freiburg and outside Wolfsburg still to come, Bayern's latest domestic triumph looks relatively straightforward, but an administrative change was needed to start the season after a weak opening.
After a shame 5-1 defeat at Eintracht Frankfurt on November 2, Bayern came in fourth on the table, four points behind early season leader Borussia Monchengladbach.
That result marked the end of Niko Kovac's 16-month reign. Flick appointed interim chief before signing a new contract until 2023 in April.
And Bayern flourished with the 55-year-old former Germany assistant.
This result means they got 58 points out of a possible 66, but the season is still far from over.
As Bayern progressed to the German Cup final, where they will meet Bayer Leverkusen on 4 July in Berlin, the five European champion teams are still in the Champions League and are well positioned to reach the quarterfinals after establish a 3-0 advantage over Chelsea in the first leg of the round of 16.
"We took the first step and achieved our big goal," added Flick.
"But we also have the cup in sight and obviously the Champions League games are something you cannot plan for and we still need to survive the Chelsea game."
Nine league titles in one club – statistics
- David Alaba and Thomas Muller win the ninth Bundesliga championship title, equaling the record set by Franck Ribery last season.
- Hansi Flick is the third person to win the Bundesliga title for Bayern, both as a player and as a manager, after Franz Beckenbauer and Niko Kovac. Flick won the Bundesliga title as a Bayern player in 1985-86, 1986-87, 1988-89 and 1989-90.
- In the top five leagues in Europe, only Juventus (35 in Serie A) and Real Madrid (33 in La Liga) have won more titles than Bayern (30, including the pre-Bundesliga era).