The welcoming ceremony in Fort Lauderdale in the US state of Florida came after Barcelona confirmed they reached an agreement with German champions Bayern Munich for the transfer of the Polish striker.
"We worked hard to get to this moment but we got there in the end," said Lewandowski in front of a cheering crowd.
"I am always hungry to succeed and have the winning mentality," he added.
"This is a new challenge for me" and "I want to do my best for the club," he also said. "I am ready to be a part of this big club with amazing history."
The Spanish club said in a statement late on Tuesday that "FC Barcelona and Bayern Munich have arrived at an agreement for the transfer of Robert Lewandowski for a total of EUR 45 million + EUR 5 million in variables."
It added that Lewandowski would sign a contract with Barcelona for the next four seasons, with the buyout clause set at EUR 500 million.
Lewandowski on Sunday joined Barcelona's squad in Miami for a tour of the United States that includes games against Real Madrid in Las Vegas, Juventus in Dallas, and the New York Red Bulls in New Jersey.
Barcelona said on their website that "the striker from Poland stands out for his goalscoring abilities."
They added that "Lewandowski will bring goals, experience and know-how to the Barça attack."
Lewandowski was in May named the top scorer in Europe's biggest football leagues last season, with 35 goals for Bayern. The Polish marksman won the annual European Golden Shoe award for the second time in a row, finishing well ahead of the rest of the pack.
Lewandowski was earlier this year crowned the top scorer of Germany's Bundesliga premier league for the 2021/2022 season, his seventh such trophy since he began playing in Germany in 2010.
The 33-year-old, who captains Poland’s national team, in January won world soccer governing body FIFA’s 2021 Best Men's Player award, beating Argentina’s Lionel Messi and Egypt's Mohamed Salah.
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Source: PAP, fcbarcelona.com