Gordon Taylor has confirmed he will leave his role as chief executive of the Professional Footballers' Association after 38 years.
Taylor, 74, has headed up the players' union since 1981 after taking over from former secretary Cliff Lloyd.
But his departure comes after the organisation announced a "full and open review" into its finances.
"I have given the majority of my life to the advancement of the PFA," he said at the PFA's annual general meeting.
The meeting, held on Wednesday in Manchester, should have taken place in November.
Taylor will remain in his post until the review is complete and presented at the following AGM.
The PFA has also said its entire management committee and current chairman Ben Purkiss will step down.
Taylor said the organisation was now "united on the best way forward".
He added: "Every decision I have made has been in the interest of members and I believe the review will make the PFA - the oldest and most powerful sporting union in the world - even stronger. It will ensure we have the right structures in place to support our former, current and future members.
"It goes without saying that I am extremely proud of the work and input that the PFA has had on the development of the greatest game in the world, and I will continue to fight for the organisation, its members and our role in the game - both in this country and worldwide."
Taylor is credited with negotiating the PFA's biggest source of income - around £25m per year from the Premier League.
The former Bolton, Birmingham, Blackburn and Bury winger made over 500 appearances in an 18-year playing career.
Taylor's biggest success story at the PFA came in 2001 while negotiating a deal with the Premier League over what the PFA's share of television revenue should be.
England internationals including David Beckham and Gary Neville were among 99% of the PFA's membership to approve strike action until a figure of £52.2m (over three years) was finally agreed, alongside stipulations relating to future deals.
Regarded as one of football's finest administrators during the 1980s and 1990s, much of the PFA's influence on the modern game can be traced back to Taylor.
Taylor established community programmes and youth training schemes (now apprenticeships) at all 92 professional football clubs.
Former England internationals Tony Adams, Paul Merson, Paul Gascoigne and Paul Ince were among the first graduates, as youth development was revolutionised and the number of schoolboys entering the game at the age of 16 doubled.
He played a key role in founding the 'Let's Kick Racism Out of Football' initiative in 1993, which later became the organisation Kick It Out.
More recently, Taylor has pushed for football to adopt the 'Rooney rule' to increase the number of black, Asian and minority ethnic (BAME) coaches in the game.
While the annual PFA Awards evening in April has gone from a men-only sportsman's dinner to an inclusive and glitzy bash, it has not been without controversy.
Football agent Rachel Anderson sued the PFA after being refused admission in 1998 and was awarded damages of £7,500, plus costs.
In 2013, black American comedian Reginald D Hunter used an offensive racist term during his performance at the Grosvenor House hotel in Mayfair, with Taylor saying the performer may have been unaware the language had been an "emotive" subject in football.
There have also been raised eyebrows over perceived lavish expenditure at times, with £1.9m spent on LS Lowry's 'Going to the Match' painting.
In 2013, national newspapers reported Taylor had run up more than £100,000 in gambling debts, and in 2015 he was forced to issue a public apology after comparing the Ched Evans rape case with the Hillsborough tragedy.
The PFA has also been criticised in several quarters for not acting quickly enough over the problem of football-related dementia, with Dawn Astle - the daughter of former West Brom and England striker Jeff Astle - walking out of a meeting with Taylor.
Around 300 high-profile former and current players endorsed an open letter calling for Taylor to step down in November amid a dispute with current chairman Purkiss.
In December, the Charity Commission said it would be "engaging" with the PFA "to establish the facts" amid criticism of Taylor.
The latest PFA Charity accounts reveal staff costs of £4m, but elsewhere in the accounts it is stated that "no salaries or wages have been paid during the year".
In separate PFA general fund accounts for 2017-18, Taylor's remuneration comes to a total of £2,020,393.
In response to the concerns, Taylor said the organisation had "listened" and had "taken the time to think carefully about what is in the best interests of our organisation and our members".
"I have dedicated the last 40 years of my life to professional football," he added.
The Taylor timeline
1981 - Takes charge of the PFA and introduces a non-contributory pension scheme for members.
1986 - Helps establish the Football in the Community initiative at six clubs before it is rolled out across all 92 Football League clubs.
1988 - Implements a Youth Training Scheme for 16- to 18-year-old players at professional clubs.
1989 - Agrees to join the Football League as chief executive before reconsidering and staying with the union.
1994 - Appointed President of FIFPro (the International Association of Football Players' Unions).
2001 - Secures a £52.2m three-year deal with the Premier League over television revenue after 99% of players back a threat to strike.
2008 - Recognised in the Queen's birthday honours for services to Football as he is appointed Officer of the Order of the British Empire (OBE).
2015 - Issues a public apology after comparing the Ched Evans rape case with the Hillsborough tragedy.
2017 - Dawn Astle, the daughter of former West Brom and England striker Jeff, walks out of a meeting with Taylor criticising the PFA for a lack of action on dementia research.
2018 - The PFA says it is "disappointing" that a dispute over the eligibility of Ben Purkiss as chairman has become public knowledge.