Sexton led the Blues to FA Cup glory in 1970 and secured their first European success in the Cup Winners' Cup the following year.
His managerial career began at Leyton Orient and from there he moved on to Chelsea, before enjoying spells in charge of QPR, Manchester United, the England Under-21 team and Coventry.
The Football Association's director of football development Sir Trevor Brooking said: "It is a sad day for English football.
"Anyone who was ever coached by Dave would be able to tell you what a good man he was, but not only that, what a great coach in particular he was.
"In the last 30-40 years Dave's name was up there with any of the top coaches we have produced in England - the likes of Terry Venables, Don Howe and Ron Greenwood.
"His coaching was revered."