Atlanta United

At the time the team was announced, Atlanta was the largest metropolitan area without an MLS franchise. Atlanta Falcons owner Arthur Blank's AMB Sports and Entertainment Group had submitted a bid for an expansion franchise in 2008, but withdrew the bid in early 2009 due to state and local government budget shortfalls and Blank's inability to find partners to build an appropriate stadium for the proposed team. On July 10, 2010, Dan Courtemanche, MLS's executive vice president of communications, said that despite the bid withdrawal, regular discussions with Blank regarding Atlanta's potential as an expansion market were occurring.

On May 31, 2011, the NHL's Atlanta Thrashers were sold to True North Sports & Entertainment, who announced that they would relocate the team to Winnipeg and rebrand as the Winnipeg Jets. The Thrashers' relocation helped restart the efforts and talks of bringing an MLS expansion team to Atlanta.

In May 2012, while the Falcons' proposed new stadium was going through the approval process, MLS commissioner Don Garber cited Atlanta as one of three "intriguing" markets for future league expansion. Additionally, when Blank presented his case for a new stadium at the Falcons' annual meeting with season ticket holders, he stated that an additional benefit of the new stadium was that it could help attract a Major League Soccer franchise and potentially host World Cup matches. Later that year, in November, Garber said if the Falcons could complete plans for a new stadium, MLS would "try to figure out how an MLS team could be part of their plans."

Rich McKay, Falcons president and CEO, said in 2013 that the team was "open to various options, including [its] ownership of a team or someone else owning a team". Dan Courtemanche said, "We are big believers in the Atlanta market," and cited the city's growing Hispanic population and corporations that could serve as its sponsors. Then, in March 2013, the city and the Falcons agreed to financing terms, and in May 2013, the Georgia Department of Economic Development board approved $30 million in bonds to finance the land purchase for the new stadium. The stadium was set to open in 2017 and could be configured for professional soccer. Atlanta remained at the top of the list for an MLS expansion team, as Garber, in the December 2013 MLS State of the League address, emphasized that it was a goal to continue to expand in the Southeast, and added, "if we can continue to advance our discussions positively with Arthur [Blank] and the [Atlanta] Falcons, we hope to be able to get a situation finalized so that could potentially be our second team. Orlando being the first, maybe Atlanta or Miami would be the second or the third." In December 2013, Garber said the league was making progress in discussions with the Falcons and that the stadium situation was finalized. Negotiations continued, as Courtemanche said in January 2014 that Atlanta "remains a great prospect for MLS expansion," and in February 2014, Rich McKay confirmed the parties were "far along in negotiations."

On April 16, 2014, Blank announced that MLS had awarded an expansion franchise to his group, and the team would begin play in 2017. Atlanta became the second franchise awarded in the Southeastern United States in five months, following the Orlando City SC announcement in late 2013. The Southeast had been without an MLS team since the Miami Fusion and Tampa Bay Mutiny were dissolved in 2001.

Atlanta's first regular season MLS game was played on March 5, 2017, at Bobby Dodd Stadium with 55,297 in attendance. Yamil Asad scored the first goal in team history in a 2–1 loss to New York Red Bulls. A week later, the team registered its first win with a 6–1 away defeat of fellow expansion team Minnesota United FC. On March 18, 2017, the team registered its first win at home, beating Chicago Fire, who went down to ten men in the eleventh minute, 4–0 in front of a sold-out Bobby Dodd Stadium. Following its move to Mercedes-Benz Stadium, the team continued leading the league in attendance and averaged more than 48,000 in its home league matches, breaking records for attendance for a non-doubleheader MLS game and average single-season attendance for a U.S. soccer team. Atlanta clinched a berth in the playoffs, becoming the third MLS expansion team to do so in their inaugural season, by finishing tied for third place in the Eastern Conference; due to tiebreaking rules Atlanta was seeded fourth. In its first playoff game, the team faced Columbus Crew and set a then-MLS attendance record for a playoff game with 67,221 spectators in attendance. After 120 minutes of scoreless action, the match was decided by a penalty shoot-out, which Columbus won 3–1 to eliminate Atlanta.

In their second season, Atlanta finished second in the Eastern Conference as well as the Supporters' Shield. The club qualified for the playoffs for the second year in a row, advancing to MLS Cup 2018 after beating New York City FC and New York Red Bulls. In the final on December 8, the team beat Portland Timbers, bringing the city of Atlanta its first major sports championship since MLB's Atlanta Braves won the 1995 World Series. The win qualified Atlanta for the 2019 CONCACAF Champions League, marking the first time Atlanta qualified for continental competition.

The win also allowed Martino, who had announced earlier in the season that he would not return for the 2019 campaign, to end his two-year tenure on a high note. Josef Martínez was named league MVP, while Martino was named Coach of the Year.

Martino left the club following their MLS Cup triumph in order to take over as manager of the Mexico national team. He was replaced by Frank de Boer. In the second edition of the Campeones Cup, Atlanta defeated Club América 3–2, winning the trophy and becoming the first club from United States to defeat a Mexican side in the cup match. De Boer led the club to wins in both the U.S. Open Cup and Campeones Cup, but after beating the New England Revolution and Philadelphia Union in the MLS Playoffs, Atlanta United were eliminated in the conference finals by Toronto FC.

The 2020 season started brightly for United, with two wins in two matches before the season was postponed due to the COVID-19 pandemic. Following a nearly four-month layoff, United participated in the MLS is Back Tournament in Orlando, Florida, losing all three of their matches. Following their elimination from the MLS is Back Tournament, De Boer and Atlanta United mutually agreed to end his relationship with the club. He was replaced on an interim basis by Stephen Glass, who led the club following the resumption of league play in August.

At the end of 2020, former Argentina international defender Gabriel Heinze signed a two-year contract to be the next head coach.

During the offseason prior to the 2021 MLS season, Atlanta United brought in 9 new players including Santiago Sosa and veteran striker Lisandro López. On April 6, 2021, United played their first game of the 2021 season, beating Costa Rican side Alajuelense 1–0. The match marked the return of striker Josef Martínez, who had missed the entirety of the 2020 season due to a torn ACL.

On April 13, 2021, Atlanta United beat Costa Rican side Alajuelense 2–0 on aggregate to advance to the quarterfinals of the CONCACAF Champions League.^[] In their largest home defeat to date, they lost the first leg of the quarterfinals to Philadelphia Union on April 27, 2021, by a score of 3–0.^[]

On July 18, 2021, Atlanta United announced the firing of head coach Gabriel Heinze, after the team hit a club-record eight-game winless streak, with only two wins out of their first thirteen games of the 2021 MLS season. Heinze's interim replacement was Atlanta United assistant coach Ronny Deila.

On August 12, 2021, former Mexican international and Seattle Sounders FC assistant coach Gonzalo Pineda was named the fourth permanent head coach in club history, with his first match away to D.C. United on August 21. Valentino remained with the club as an assistant coach.

On November 7, 2021, Atlanta United clinched a spot in the 2021 MLS Cup Playoffs after a 2–1 victory over FC Cincinnati at TQL Stadium. They were then knocked out in the first round by New York City FC.

Atlanta United finished 11th in the Eastern Conference in the 2022 season and did not qualify for the playoffs. Atlanta United participated in the 2022 U.S. Open Cup as defending champions, as the 2020 and 2021 editions of tournament were canceled due to the COVID-19 pandemic. They were knocked out in the Round of 32 by Nashville SC. At the end of the season, after winning the award for the 2022 MLS Goal of the Year, Josef Martínez did not renew his contract with Atlanta United, subsequently leaving the club after six seasons.

Atlanta United finished 6th in the Eastern Conference in the 2022 season and were knocked out in Round One of the MLS Cup Playoffs by the Columbus Crew. Atlanta United competed in the 2023 U.S. Open Cup and also participated in the 2023 Leagues Cup for the first time in their history. They were knocked out of the 2023 U.S. Open Cup in the Third Round by Memphis 901 FC. They were also knocked out of the 2023 Leagues Cup in the group stage. Their top scorer in all competitions was Giorgos Giakoumakis with 19 goals.

On June 3, 2024, Atlanta United announced the firing of head coach Gonzalo Pineda, after the team lost a club-record 5 consecutive home matches. Pineda's interim replacement is Atlanta United assistant coach Rob Valentino, who led the team as an interim head coach after Gabriel Heinze was fired in 2021. In the summer transfer window, Atlanta sold Thiago Almada for a reported fee of $22 million, plus $3 million in add-ons; which broke the transfer record for the MLS. They also sold Giorgos Giakoumakis and Caleb Wiley, which resulted in Atlanta United having over $50 million to spend in the summer transfer window On October 19th 2024, Atlanta United Surprisingly qualified to the Wild-Card Round by beating Orlando to face Montreal on October 22nd in which they won on penalties. On the 25th of October 2024, they played Inter Miami in the First Round who had a record breaking season in which they had the most points in a single MLS Season to win themselves the supporters shield, Atlanta lost in Miami 2-1. While on November 3rd 2024, After a shaky start Atlanta came back to win 2-1 at Home against Miami. On November 9th 2024, Atlanta United faced a decisive match against Miami to decide who plays Orlando in the Conference Semi-finals in which Atlanta won 3-2 in Miami. On November 24th, 2024, Orlando beat Atlanta 1-0 ending their run in the MLS Playoffs.