Nicola Cortese has dismissed manager Alan Pardew despite Saturday’s 4-0 win over Bristol Rovers.
Dean Wilkins, previously a member of Pardew’s coaching staff, has been named caretaker boss and will be assisted by under-21 coach Martin Hunter.
First-team coach Wally Downes and goalkeeping coach Stuart Murdoch have also been relieved of their duties.
Saints, who started the season as favourites to win promotion, are currently 14th in the League One table.
“The club has decided that, to achieve its well known targets, it is essential to make changes to the management,” said a Southampton statement.
“We recognise that frequent changes to the football management are unlikely to assist in the winning of trophies and promotions.
“However, we are taking these steps to achieve our aims, which we share with all supporters, to get promoted this season, and secure long term stability and progress for our football operations”.
There was speculation that Pardew would lose his job at the end of last season but the 49-year-old remained in charge and strengthened his squad in the summer, signing the likes of Ryan Dickson, Frazer Richardson and Danny Butterfield.
Supporters will question the timing of the move given there is just one day remaining of the current transfer window.