Leyton Orient manager Justin Edinburgh died on Saturday aged 49, after suffering a cardiac arrest a few days ago.
Edinburgh, the former Tottenham Hotspur defender, joined League Two side Orient as coach in 2017 and led the club back into the Football League as National League champions in April.
"We are completely heartbroken by this tragedy," Orient chairman Nigel Travis told the club's website. "The success that Justin brought to Leyton Orient was incredible, but more importantly the impact he had on us all as a winner and a wonderful, inspirational human being will be his legacy and will stay with us forever."
Edinburgh started his playing career at Southend United before he moved to Tottenham in 1990. He made 215 appearances for Spurs, helping them win the FA Cup and League Cup during a decade at White Hart Lane.
He went on to finish his professional career at Portsmouth before beginning his managerial career in 2003, with spells at Billericay, Fisher Athletic, Grays Athletic, Rushden and Diamonds, Newport, Gillingham and Northampton.
It is with profound and utmost sadness that Leyton Orient announces its manager Justin Edinburgh has passed away.#LOFC #OnlyOneOrient
— Leyton Orient (@leytonorientfc) June 8, 2019
"At a time when he should be celebrating the success of his team and preparing for the rewards of league football next season, he has been lost to the game and to his community too soon," said Howard Wilkinson, the chairman of the League Managers Association.
"Justin will be remembered by all in the game as a true professional. A hard-working man who became successful as a player at the highest level of the game and turned his love of football into a life-long career as a coach and as a manager."
He also led Orient to the FA Trophy final at Wembley last month, where they were beaten by AFC Fylde.
Tottenham paid tribute to their former player, saying: "We are deeply saddened and shocked to hear of the passing of Justin Edinburgh. Our heartfelt condolences and thoughts go out to his family and friends at this terribly difficult time as well as everyone that worked alongside Justin at Leyton Orient."