New York City FC will play in America's top football league, Major League Soccer, from the 2015 season.
Edelman will help the club engage fans across New York City's five boroughs, support community efforts, and create buzz for the team's debut.
The club, which would become MLS' 20th team in 2015, is jointly owned by baseball team New York Yankees and Manchester City.
Edelman will also work to incorporate the values of both the Yankees and Manchester City into its outreach to connect with fans on a more intimate level.
"New York City has built so many great sports teams, and both the New York Yankees and Manchester City have a tremendous history of accomplishments," said agency president and CEO Richard Edelman, in a statement.
The team is still without a home. In August, the club reportedly filed plans to build a football stadium in the Bronx, near Yankee Stadium. Residents and elected officials had previously objected to the club constructing a stadium in Flushing Meadows Corona Park in Queens.
Edelman's research and analytics subsidiary Edelman Berland is working with New York City FC on research initiatives to help the franchise understand the market in New York and build its fan base.
Additional information about the account was not disclosed.
Last month, New York City FC hired Droga5 as its advertising agency, working on fan activation and engagement projects.
Retired English football superstar David Beckham will work to establish a team in Miami in coming years that would become the league's 21st club, according to the Associated Press.