The former Everton defender only took charge of the Paisley club in June
Alan Stubbs has been sacked as St Mirren boss.
The struggling Ladbrokes Premiership side have suffered three successive defeats and are second from bottom in the table.
Stubbs, previously manager at Hibernian and Rotherham, was appointed boss of the Paisley side in June following the departure of Jack Ross to Sunderland.
A statement from St Mirren read: “Careful consideration was given to this decision and the search for a new manager will begin immediately.
“The club would like to thank Alan for his work during his time in charge at The Simple Digital Arena and wish him the best for the future.
“The club will keep supporters informed as new arrangements are put in place and thank them for their patience and ongoing support.”
Saturdays 4-1 defeat at pacesetters Hearts means only Dundee – who Stubbs team beat on the opening day of the season – are below St Mirren.
Their next match is a home game against champions Celtic on Friday, September 14.
Stubbs, a 46-year-old former defender, made nearly 500 appearances in an 18-year playing career with Everton (twice), Celtic, Bolton, Sunderland and Derby.