The announcement was made by Chennaiyin FC co-owner Vita Dani, who said: "It is an absolute honour to have the legendary M.S. Dhoni as one of the co-owners of our franchise, Chennaiyin FC.
"Dhoni has a strong association with the people of Chennai and so with him coming on board, we take another giant step towards achieving the goal of creating a world class football club in Chennai."
Dhoni said: "I used to be a goalkeeper in school and always enjoyed playing and watching the game. I wanted to be associated with football, so when the opportunity came to be a part of Chennaiyin FC I was ecstatic as this gives me a chance to connect with the city of Chennai again. I have played franchise cricket for this city so I know how supportive they are."
"I am sure all the players of Chennaiyin FC will see how much love Chennai gives to their players. The Hero Indian Super League is a fantastic platform for football to grow with so many big names, IMG-Reliance and Star India associated with it.
"I look forward to an exciting season ahead, but at the same time, it is important that we develop the grassroots level and produce more football stars in India."
Chennaiyin FC starts their Hero Indian Super League campaign with an away game against FC Goa on October 15 while their first home fixture is against Kerala Blasters on October 21.