Saints have decided it is time to part company with director of rugby Jim Mallinder with chairman John White stressing 'the time was right for some change'.
Mallinder had seen his side lose nine of their past 10 matches in all competitions and the board has now decided to act.
Attack coach Alan Dickens will take temporary charge of the team until a replacement is found.
The rest of the coaching setup remains unchanged at the current time.
Mallinder's departure is a seismic moment as he has been at Saints since the summer of 2007.
He helped the club to promotion after an unbeaten season in what is now the Championship during his first season in charge.
Saints went on to win their first Aviva Premiership title in 2014 as well as securing two Challenge Cup crowns and an Anglo-Welsh Cup title.
They reached the Heineken Cup final in 2011, leading 22-6 against Leinster at half-time before the Irish giants stormed back to claim a 33-22 victory in Cardiff.
But the past couple of seasons have been tough for Saints, who had finished top of the Premiership for the first time in 2015.
They finished fifth in 2016 and seventh earlier this year, and they are currently 10th in the standings.
They are bottom of their Champions Cup pool after last Saturday's 43-32 defeat to Ospreys at the Gardens.
And White said: “Jim has been an outstanding director of rugby.
"We have been very lucky to have him at Franklin’s Gardens and he will always be a part of the Saints family.
“This is not a decision that has been taken lightly, but the board and major shareholders felt that the time was right for some change.”
And Saints chief executive Mark Darbon said: "Jim has done a superb job as Northampton Saints’ director of rugby over the last decade, and the amount of silverware the club has won during his tenure speaks for itself.
"We thank Jim for all he has done at Franklin’s Gardens.
“We will now begin an extensive search to find a world-class director of rugby to replace Jim.
“Whilst that search is underway, we will look to bolster our existing coaching group with some additional leadership and experience on a short-term basis for this season.
“Alan Dickens will oversee rugby and coaching matters on temporary basis as interim head coach.”