Lewandowski is the highest profile of Barcelona's numerous summer recruits, which also includes Raphinha, Frank Kessie, Andreas Christensen and Jules Kounde.
The Poland international scored 50 goals across all competitions in his final season with Bayern Munich before moving to the Camp Nou.
Barcelona have not won a trophy since winning the Copa del Rey in the 2020/2021 season under Ronald Koeman.
Their last La Liga title was under Ernesto Valverde in the 2018/2019 season while the last time they were crowned Champions of Europe was under Luis Enrique in the 2014/2015 campaign.
Lewandowski believes a club of Barcelona's stature should not wait too long to lift major trophies.
"I think it's been too long for Barcelona without winning titles," he said via quotes reported in Marca. "I'm sure we're going to win them.
"When I first knew that Barcelona were interested in bringing me to the club, at all times I thought it was the perfect time, for me and for the club.
"I didn't want to play my whole life in one league. In the Bundesliga, everything went well, it was a good experience for me, but I knew it was another step for my career to go to LaLiga."
Lewandowski did not find the back of the net when Barcelona started their season with a disappointing goalless draw against Rayo Vallecano last weekend and will be hoping to make amends when they travel to Real Sociedad in their next match.
