The Visitor controlled the game, with Muller scoring his seventh career goal against Barca.
Lewandowski made sure of the win with a typical predatory finish,
poking his 74th Champions League goal into an empty net after Jamal Musiala’s drive had cannoned back off the post.
His 75th came late in the game, as he once again showed his talent in front of goal.
As he lashed finish after Serge Gnabry’s shot had come back off the post and fell to him in the box.
Barca, playing their first Champions League since the departure of talisman Lionel Messi.
They ended the game with four teenagers on the pitch, which did at least inject some urgency and lift a subdued crowd of just short of 40,000 because of Covid-19 restrictions.
They were still thoroughly outclassed, though, and by a Bayern team that were not even at their best.
The German side lead the group, with the other game, between Benfica and Dinamo Kiev, finishing 0-0.
Bayern ease to win against broken Barca
It is now 13 months since Bayern ruthlessly exposed the growing frailty at the heart of Barcelona.
Putting eight past them in one of the most eye-opening Champions League knockout games in recent memory.
Messi started up front with Luis Suarez in that 8-2 loss in 2020. On Wednesday.
Barca paired two former Premier League failures in Memphis Depay and Luuk de Jong.
And that was largely because ex-Middlesbrough forward Martin Braithwaite is injured.
Bayern are now undefeated in 19 European away matches.
A record run in all European competitions – and will surely only get better.
As for Barca, they are stalling and it is hard to see how they get themselves back on track.
Second place in Group E is far from a sure thing.