The Bavarians moved 10 points clear of second-placed Borussia Dortmund, who have three games left to play, and secured an eighth consecutive league crown.
In a rollercoaster season that saw coach Niko Kovac fired in November with Bayern off the top spots and Hansi Flick taking over, Bayern turned it around after the winter break, are unbeaten since and won their last 11 straight league matches.
Werder, desperate to avoid their second relegation after 1980, were bold and matched the Bavarians in the first half for speed and possession.
They also had the better chances until Bayern winger Kingsley Coman’s glancing header in the 24th.
The Bavarians gradually gained ground and broke the deadlock with defender Jerome Boateng’s superb pass for Lewandowski, who turned in the box and grabbed his 31st goal of the campaign just before halftime.
The Polish forward, who scored on his return from suspension for Bayern, is chasing the 40-goal record for one season set by Gerd Mueller in 1972 and had a string of good chances after the break to add to his tally.
But it was keeper Manuel Neuer who proved key for Bayern after they were left with 10 men for the final 10 minutes following the dismissal of Alphonso Davies, making a sensational one-handed save to ensure yet another league title
Eighth consecutive German title
Bayern have won seven out of seven of their league games since action resumed amidst the coronavirus pandemic, allowing them to pull away from rivals Borussia Dortmund.
A 1-0 win at Signal Iduna Park courtesy of Joshua Kimmich’s stunning chip proved a crucial result in the title race, while fellow challengers RB Leipzig and Borussia Monchengladbach also faded away.
Hans-Dieter Flick had taken over in the Bayern dugout after the catastrophic 5-1 defeat to Eintracht Frankfurt, which saw 2018/19 Bundesliga-winning Niko Kovac get the chop.
And after initially losing games to Bayer Leverkusen and ‘Gladbach, the champions didn’t look back with a 100% record since December 7 aside from a goalless draw with Leipzig.
Title glory now gives Bayern the opportunity of securing a domestic double against Leverkusen in the DFB-Pokal final as well as challenging in the Champions League when its return is confirmed.
There’s a real feeling that Bayern could be a major player not only in Germany, but also in Europe, particularly with their star man Lewandowski emerging as an early favourite for the Ballon d’Or.