His efforts there earned him a move to the Allianz Arena, and the 29-year-old has maintained a remarkable strike rate in Bavaria.
Lewandoswki was among the goals again on Saturday, as he became a Bayern centurion, with a brace bagged in a 4-0 victory over Mainz.
Those efforts took him onto 82 for the club in German top-flight competition – a record haul which has eclipsed the 73 efforts managed by World Cup winner Rudi Voller for Werder Bremen in the same period of time.
While Lewandowski remains a talismanic presence for Bayern, there have been signs of late that cracks could be appearing in the relationship between club and player.
The Pole has been outspoken in his views of a transfer policy he fears will leave the reigning Bundesliga champions trailing in the wake of their big-spending European rivals.
Bayern have not taken too kindly to the comments, with CEO Karl Heinz-Rummenigge telling Bild: “Obviously Robert was irritated by PSG's transfers. He is employed with us as a football player and earns a lot of money. I regret what he said. Whoever publicly criticises the club or his team-mates will get in trouble with me personally. He already made false claims last season following the Freiburg match, where he claimed he had not been supported enough.”
Lewandowski suggested at the end of the 2016-17 campaign that he had been unable to snatch the Golden Boot away from Dortmund’s Pierre-Emerick Aubameyang due to a lack of support from his team-mates.
He still managed to net 30 league goals, and 43 in all competitions, and already has nine in seven appearances this season.