Brought in the summer, Wellens - a legend during his playing days at Rovers - has presided over a hugely different start to the League One season.
Doncaster have been in the relegation zone throughout the campaign, with their away form having been particularly pitiful. Rovers have lost ten out of 11 league games, scoring three times and conceding 26 goals.
They have won just three times in 19 matches this term and followed up a poor 2-0 weekend loss at Burton with meek elimination in the Papa John's Trophy at Crewe on Wednesday night, with Wellens's assistant Noel Hunt speaking to the press after the game.
Under 18s manager Gary McSheffrey will take charge of the team for Saturday’s FA Cup tie at home to Mansfield Town. He will be assisted by Frank Sinclair.
A club statement read: "The club’s board have taken the decision that change is required at this time in order for a permanent appointment to be made in time for the opening of the January transfer window."
The recruitment process will begin in earnest on Monday with a view to making an appointment before Christmas.
Wellens had been in charge for 199 days.