Lewandowski left Barcelona upon the expiration of his contract at the end of the 2025-2026 season.

Although he is not featuring at the World Cup, with Poland having failed to qualify, he will soon be plying his trade in North America.

He has penned a contract through to the end of the 2027-2028 MLS season.

Gregg Berhalter, Chicago's director of football and head coach, said: "From the day Joe Mansueto and I met for the first time, we set out to build a world-class club that inspires greatness, unites Chicago and wins championships. Robert embodies those values and represents the standards this city deserves: a champion and a competitor.

"His arrival reinforces our ambition to compete for trophies and raises the standards for the club to heights worthy of this city.

"We cannot wait to get to work with him and have Chicago see first-hand why he is among the most revered sporting icons in the world."

Lewandowski has netted 629 goals in 869 club games.

The 37 year-old scored 120 goals in 193 matches for Barcelona, after his move there from Bayern Munich in 2022.

Lewandowski holds the record for the most goals in a single Bundesliga season, plundering 41 goals in 29 top-flight appearances in the 2020-2021 campaign for Bayern.

His former Bayern team-mate, Muller, joined the Vancouver Whitecaps last year, while Messi has been starring for Inter Miami since 2023.

Chicago's first game back after the World Cup break is against the Whitecaps, though it remains to be seen whether Lewandowski will be fit to feature against his old strike partner Muller.