The invaluable three points takes the Merseyside outfit two points clear of title rivals Manchester City in second, though Liverpool have played a game more.
Bayern overtook Dortmund by one point and with Robert Lewandowski in great form, Niko Kovac’s men will now take some stopping in the final six matches.
How it all looked so different in December, when Dortmund led Bayern by a sizable nine points.
His team trailing by two goals to Wolves in the FA Cup semifinals with time running out, Watford manager Javi Gracia needed quick inspiration from one of his players.
Lewandowski became just the fifth player to achieve the feat and only Gerd Muller got there quicker.
Dortmund had the first real opportunity within 10 minutes in Munich but Mahmoud Dahoud struck the post.
They were made to pay as another former Dortmund player, Mats Hummels, headed home the opener from a corner – one of Bayern’s 11 in total – in the 10th minute.
An understandably much hyped affair given the importance of the match, the 100th Bundesliga “Klassiker” was realistically over when Lewandowski made it 2-0.
Centre back Dan-Axel Zagadou seemingly didn’t spot a lurking Lewandowski and his pass was intercepted by the front man, who then beat Roman Burki with a typically composed finish.
Javi Martinez and Serge Gnabry made it 4-0 prior to the interval and Lewandowski tallied his second in the 89th to give Bayern a staggering 22 goals in their last four home games.
“We played perfectly over the 90 minutes,” Kovac told the Bundesliga’s website. “I think you can say it’s a deserved result but we could have and should have won by a greater margin when you look at the chances and corners we had.
“Today we showed in every department what we want to see, what I expect, what the benchmark is, the way we played at the start of the season – and we showed that again today.”
Both clubs were able to steady after being knocked out in the Champions League by English opposition but Dortmund are sure to be reeling again.
“We were given a lesson,” Dortmund manager Lucien Favre told the club website. “We need to concentrate on our upcoming games now. We need to give our best.
“If we play like we did today, it will be difficult, that’s clear.”
Barcelona realistically seal Liga title
The race isn’t as close in Spain, where Barcelona realistically sealed the title by beating 10-man Atletico Madrid 2-0 at home after netting twice in the final five minutes.
A win for second-place Atletico would have seen Diego Simeone’s well organized side move to within five points of Barcelona but the chances of that happening all but disappeared when fiery striker Diego Costa was shown a straight red card in the 29th minute after appearing to say something to referee Jesus Gil Manzano.
He was escorted off the pitch by Barcelona defender and Spanish international teammate Gerard Pique.
A string of saves by Atletico keeper Jan Oblak kept it scoreless until Luis Suarez’s curled effort from outside the box in the 85th minute.
One minute later, Lionel Messi sprinted down the right side, lost possession, got the ball back and beat Oblak with a low finish for 2-0.
Barcelona – which travels to Manchester United in the first leg of the Champions League quarterfinals Wednesday – now leads Atletico by 11 points with seven rounds remaining.
Meanwhile Real Madrid avoided a second straight defeat under Zinedine Zidane by coming back to beat Eibar 2-1 at home.
Man City quadruple still on
Manchester City, managed by former Barcelona and Bayern boss Pep Guardiola, is still on course for the quadruple after reaching the FA Cup final thanks to a narrow 1-0 win against Brighton at Wembley Stadium.
Gabriel Jesus’ header in the fourth minute from a Kevin de Bruyne cross suggested the floodgates might open in London but Brighton – relegation threatened in the Premier League – limited the damage.
The Seagulls’ lone opportunity came early in the second half when City defender Aymeric Laporte cleared near the line with striker Glenn Murray about to put the ball into an open net.
Already with the League Cup in hand, City will be the substantial favorite in the final next month when they face either Watford or Wolves. They battle Sunday in the second semifinal.
Guardiola’s side trail Liverpool by a point in the league with one fewer game played.
City will next though turn its attention to Tuesday and the first leg of the Champions League quarterfinal against Tottenham.