Argentine midfielder Gaitan joins Chicago Fire
"We have wanted to add another attacking piece and believe Nico's dynamism and play-making ability could be a perfect fit," said Chicago Fire president and general manager Nelson Rodriguez.
Gaitan spent the bulk of his professional career in Portugal and Spain, making 152 appearances for Benfica between 2010 and 2016 before joining Atletico Madrid.
The midfielder won three Portuguese titles and five Portuguese League Cups during his time with the Lisbon club.
He then went to Atletico from 2016 to 2018 before heading to China.
"Nicolas is a player that can destabilize any defense in this league," Chicago Fire head coach Veljko Paunovic said.
"He has an enormous amount of talent and is still in his prime. We're eager to get the most out of his attacking creativity."
Gaitan has made 16 international appearances for Argentina since 2009.
Chicago made history after winning the MLS Cup in their debut year in 1998 but have not managed to return to the league's showpiece game since 2003, when they were beaten...