Everton posted a statement on X, formerly Twitter, which read: "Everton Football Club is in mourning following the death of Chairman Bill Kenwright CBE, who passed away peacefully last night aged 78, surrounded by his family and loved ones."
Kenwright had worked at the club since 1989, when he became a board member at Goodison Park.
In 1999, on Boxing Day, his consortium acquired the club, and he had been chairman since 2004.
Under his stewardship, Everton achieved a top-four finish in 2005, a run to the FA Cup final in 2009, and European qualification on six occasions.
The Toffees also completed 12 top-eight finishes, although recent seasons have not been quite as comfortable, with relegation a looming threat at Goodison Park, particularly in 2022-23.
The club issued a touching tribute to Kenwright in their statement announcing his death, saying: "The club has lost a chairman, a leader, a friend, and an inspiration. The thoughts and prayers of everyone at Everton are with his partner Jenny Seagrove, his daughter Lucy Kenwright, grandchildren and everybody who knew and loved him."
Kenwright had a remarkably colourful life as a theatre producer, helping bring hits such as Blood Brothers and Fame to the West End of London, earning the millions required to buy his beloved Toffees.
He was honoured with a CBE in 2001 for his services to film and theatre, and is survived by his daughter and two grandchildren.