The 34-year-old, who joined Barcelona from Bayern Munich in the close season, scored 57 goals in 56 matches for club and country last term.
He was the top-scorer in the Bundesliga with 35 goals.
Lewandowski also won the award last year when it was presented for the first time, after breaking the Bundesliga scoring record for a single season, previously held by Mueller, with 41 goals.
But he is yet to win the Ballon d'Or itself, having narrowly missed out to Lionel Messi 12 months ago.
The Pole would have been a strong favourite to take the honours in 2020, but the ceremony was controversially scrapped due to the effect of the coronavirus pandemic on the football calendar.