Nottingham Forest owner Nigel Doughty was found dead at his home on Saturday. He was 54.
The club said Doughty was found in the gym at his Lincolnshire house.
As well as wife Lucy, Doughty leaves behind four children, three boys and a girl.
"It is with enormous sadness that Nottingham Forest announce the death of the club's owner Nigel Doughty," the club said in a statement.
"Mr Doughty, who was 54, was found dead earlier today in his gym at his home in Skillington, Lincolnshire.
"The club would like to appeal for the privacy of Mr Doughty's family to be observed at this sad time. The club will be making no further comment."
Life-long Forest fan Doughty stepped down as chairman in October after a decade in the job following the sacking of former England manager Steve McClaren.
He was replaced in the role by former Forest player and manager Frank Clark.
Doughty, who saved the Reds from administration when he bought the club for £11million in 1999, has invested almost £100million of his personal fortune in the club.
Labour leader Ed Miliband led the tributes to "kind and generous" Doughty.
Miliband spoke of his shock after hearing the news and wrote on social networking site Twitter: "I am shocked and saddened to hear of Nigel Doughty's death. I was with him only a week ago and he was full of life, enthusiasm and vigour.
"He was a kind, generous man with a deep desire to make the world a better place. My heart goes out to his wife Lucy and his children.
"We mourn his death deeply and will sorely miss him."
Alastair Campbell, the former Downing Street communications chief under Tony Blair posted on Twitter: "Cannot believe the news about Nigel Doughty. Spoke to him Tuesday and he seemed really well. Great friend of Labour and of football. RIP."
During his 10 years at the City Ground, the club won promotion back to the Championship in 2008, three years after their relegation.
Under manager Billy Davies, the Reds reached the play-offs in each of the last two seasons.
Forward Garath McCleary praised Doughty for the work he did, saying: "He has done so much for Forest, which was not always best appreciated. My thoughts are with his family."
Nottinghamshire and England cricketer Stuart Broad added: "He was a lovely man and did a huge amount for Forest."
Former Forest striker and television and radio pundit Stan Collymore said: "Nottingham Forest owner Nigel Doughty has sadly passed away today. Condolences to his family and friends I'm sure from everyone at #nffc."
Doughty Hanson & Co, the company of which Doughty was a co-founder, issued a statement on Saturday evening, which said: "On behalf of Dick Hanson, and all the management and staff of Doughty Hanson, we are tremendously sorry to learn of the death of Nigel Doughty at home this afternoon.
"Our thoughts are very much with his family at this time."
