Drivers of the manufacturer have indicated a new body style would be coming for 2019, as Toyota and Chevrolet have significantly changed their body styles since 2017, and Ford driver Brad Keselowski has been vocal about the need for a change in order to keep up with the competition.
Ford follows Chevrolet's move to the Camaro this year in putting its muscle cars in NASCAR's top series. Ford has used Mustang as its body style in the Xfinity Series since 2011.
"Mustang is a car that is woven into the fabric of our country, and it's only right that we put it on the track in NASCAR's most visible series," Ford board member Edsel B. Ford II said. "I can't wait."
The Mustang is still going through initial testing and will be formally submitted to NASCAR for approval this summer. A public unveiling of the finished product will follow.
This will be Ford's fourth Cup model in NASCAR's modern era (since 1972), following the Thunderbird, the Taurus and the Fusion.
Ford supports six NASCAR Cup organizations that field a combined 13 cars in the series: Team Penske, Stewart-Haas Racing, Wood Brothers Racing, Roush Fenway Racing, Front Row Motorsports and Go Fas Racing.
Ford holds spots second through sixth in the current NASCAR Cup Series standings: Joey Logano is second, followed by Kevin Harvick, Clint Bowyer, Keselowski and Ryan Blaney. Kurt Busch is 10th and Aric Almirola is 11th.
Harvick has won three of the eight races this year. Bowyer has won one.
The Associated Press contributed to this report.