Heinze arrives in Atlanta from Vélez Sarsfield in his native Argentina, where he'd been manager for the last three years.
The 42-year-old has managed three clubs in Argentina since the end of his celebrated playing career - which included stints with clubs such as Real Madrid, Manchester United and Paris Saint-Germain - in 2014. His club finished third last season in Argentina, and sixth the year before, both good for qualification into continental competitions.
“I’m excited to be taking on this new challenge with Atlanta United,” Heinze said in a statement. “I believe that my football philosophy is aligned with the vision of the club and their structure and facilities are world-class. I can’t wait to meet the players, the staff and the fans and get to work in 2021.”
Club President Darren Eales described Heinze as "one of the top coaches in South American soccer" and said his "playing philosophy and commitment to youth development closely align with our ideas at Atlanta United."
Atlanta United's vice president and technical director, Carlos Bocanegra, said Heinze would employ the "aggressive, attack-minded style of play" that "aligns with the identity of our club."
It will hearken back to the team's first head coach, Gerardo "Tata" Martino, who led the team to their first MLS championship in 2018 through a style of play that emphasized flair and attacking skill. It was beloved by fans and helped shoot the club's biggest star, Josef Martinez, to the top of the MLS goal scoring charts.
de Boer subsequently brought in a more reserved style that wasn't embraced by fans, and, while Atlanta won the 2019 U.S. Open Cup, over the last two years the club has declined from the heights Martino led them to.
As a player, Heinze won league titles in England, France and Spain, and was a mainstay for the Argentina national team, playing in the 2006 and 2010 World Cups.
A defender, he earned a reputation as a fiery player and was famously referred to by Manchester United legend Roy Keane, his teammate, as a "nasty f*****." He meant it somewhat admiringly, and also noted Heinze was a "good guy."
According to Atlanta United, he will be formally introduced during a Zoom press conference on Monday, Dec. 21.