The news was widely trailed on Friday morning but it took until Saturday evening for negotiations over the terms of the 53-year-old's departure to be agreed.
In announcing it, the Blades stressed they had no plans to break up the squad with the departure of its popular and innovative manager, and they will retain his assistant, Alan Knill, and the rest of the coaching staff, who will work under caretaker Heckingbottom.
“The club will turn its attention to completing the season as strongly as possible and if we are relegated, to preparing for the Championship,” said a club statement. “We confirm our intention to keep the core of the player group together and will continue to invest further in the academy and the first team, to place us in the best possible position for the future.”
As expected, former Leeds United and Barnsley manager Heckingbottom, will take charge of Sunday's Premier League game at Leicester City but more surprisingly he has been given the job until the end of the season. Jason Tindall, sacked months into his first managerial post at Bournemouth earlier this season, will join him on the coaching staff.
Heckingbottom joined the Blades as under-23s manager last year.
The level of investment in the football side of the club and the failure to properly discuss plans for next season – at least according to Wilder – were some of the bones of contention which led to the manager's departure after five years in charge.
Wilder has spoken on numerous occasions recently about the need to retain the core of the squad and add to it when the seemingly inevitable relegation occurs this summer.
The parting was amicable enough for Wilder to provide a comment for the statement announcing his departure, talking about “a special journey and one I'll never forget.”
In 2016 boyhood fan Wilder returned to manage the club he made over 100 appearances for in two spells between 1986 and 1999 and before that served as a ballboy for the start of their sixth season in League One. He led them to promotion in his first season, and his third, winning the League Manager's Association's manager of the year award as they returned to the Premier League for the first time since 2007. They finished ninth in 2019-20.
As well as results, the style of play was also widely praised, based around a highly unusual take on the 3-5-2 formation involving overlapping central defenders. His "tough love" approach to his players was also refreshing.
Wilder became only the sixth manager in the club's history to take charge of 200 league games, and he and Knill were awarded new long-term contracts last season.
This campaign has been very different, though, bottom of the table throughout and needed a miracle from the last 10 games to avoid relegation, although they are in the quarter-finals of the FA Cup. Having reached his 99th win in charge in July, it was January before he got into three figures.
But it was less that than behind-the-scenes tensions which led to a parting of the ways on Saturday evening.
Wilder was a strong advocate of the infrastructure around the club catching up with the rapid rise of the first team, yet work is still to start on a new training ground building due to be built by the end of last year.
The investment he hoped for in the team was also not forthcoming, missing out on a host of transfer targets in the summer window, and refused the opportunity to sign a replacement when Jack O'Connell, one of those trademark overlapping centre-backs, picked up a long-term injury days before the transfer deadline.
He was also prevented from making signings in January.
Wilder was also understood to be frustrated the Blades were not offering what he thought were competitive wages, despite owner/chairman Prince Abdullah bin Musa’ad bin Abdulaziz Al Saud's claims to the contrary.
Wilder's willingness to express his unhappiness in public did not endear him to the board, who felt he did not spend the money he was given last summer wisely. The Blades broke their transfer record to sign £24m striker Rhian Brewster, who is yet to score for them.
There were rumours, denied by the club, recruitment might be taken out of the manager's hands and given to a new director of football. Wilder was always fiercely protective of his hands-on involvement in all areas, an increasingly unusual situation in the modern game.
Although he handed 16-year-old striker Antwoine Hackford his Premier League debut in January, Wilder was by and large reluctant to throw young players into his injury-hit squad this season - at least not on the field - as he was concerned about the damage it could do to their development.
Chief executive Stephen Bettis has suggested there may now be a change of course.
"The club sees the following months as an opportunity to further develop some of our talents at the academy and to give them valuable time to train with the first team," he said.
"Additionally, Jason has a fantastic pedigree and his fresh input will hopefully add a different dimension when he joins the club on Monday. He will have a watching brief at Sunday's game at Leicester."
You can read comment and analysis from chief football writer Stuart Rayner on the problems that led to Wilder's departure HERE and columnist Sue Smith on what he brought to his boyhood club and English football HERE.
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