Wilson oversaw 44 wins, 40 draws and 37 defeats at Swindon
Danny Wilson has resigned as manager of Swindon Town, who will appoint his successor within 24 hours.
The 51-year-old, who took over in December 2008, guided them to the League One play-off final last season but leaves them in the relegation zone.
He told the club website: "This allows the board an opportunity to appoint a new manager while there are still sufficient games left this season.
"Maintaining League One status has to be the priority for everyone."
The former Barnsley, Sheffield Wednesday, Bristol City, MK Dons and Hartlepool boss guided the Robins to 16th in his first half season in charge before leading them to fifth last season and a 1-0 Wembley defeat by Millwall.
However striker Billy Paynter and captain Gordon Greer left the County Ground in the summer and the side struggled even before this season's top scorer Charlie Austin departed in the January transfer window.
Wilson's 121-game reign ended with a 4-1 defeat by Southampton on Saturday and Tuesday's results dropped them back into the bottom four.
I have the utmost respect for Danny Wilson and have greatly enjoyed working within him these past 26 months - reaching the League One play-off final last season was a true highlight
Swindon chairman Andrew Fitton
Chairman Andrew Fitton said: "The club will be announcing a replacement for Danny within the next 24 hours. It will be a proven, senior manager whose prime responsibility will be to ensure our League One survival by the end of the season.
"I have the utmost respect for Danny Wilson and have greatly enjoyed working within him these past 26 months - reaching the League One play-off final last season was a true highlight.
"Unfortunately this season we have not enjoyed the consistent playing success that we all anticipated and our current league position makes for uncomfortable reading.
"Therefore, following discussions with Danny during the last 24 hours, he offered to resign from his position, acknowledging that the appointment of a new manager should inject a fresh momentum that will pull the club out of the relegation zone.
"I cannot thank Danny enough for his contribution to the club's playing fortunes but more importantly for the very professional manner in which he has conducted himself over these discussions.
"He leaves the County Ground with his head held high."
Wilson added: "Naturally, I am bitterly disappointed to be leaving Swindon, especially after last season's success, but I know that football is a results-driven game, and unfortunately in the past two months the results have just not been good enough.
"I have greatly enjoyed my time with the club and am sorry to leave but I understand and appreciate that tough decisions have to be made - they are tough on any board, and tough on any manager."
Assistant manager Peter Shirtliff has also left the club, while goalkeeping coach George Wood is staying.
Watch Wilson's last game in charge, a 4-1 defeat at Southampton
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