Sean Dyche had been the manager of the club for 10 years.
The team is four points from safety. They have lost their last seven games in the league, the last one being a 2-0 defeat to Norwich on Sunday.
U23s coach Mike Jackson, aided by academy director Paul Jenkins, U23s goalkeeping coach Connor King and club captain Ben Mee, have been asked to take charge of the team for the game against West Ham.
Sources close to the players tell Sky Sports that Dyche had not lost the dressing room.
Dyche has spent nearly a decade as a manager in the Premier League. He took over at Burnley from Eddie Howe in October of the same year after temporarily joining the England U21 backroom staff.
The last time he led a team from the Championship was in the 2015/16 season.
He signed a new four-year deal with the club in September of last year. It was the first time in 51 years that the club had secured a place in the top flight and the best finish since 1974.
The team finished in 17th place in the previous season. This was 11 points clear of the bottom three.
Alan Pace said in a statement: "We would like to place on record our sincere thanks to Sean and his staff for their achievements at the Club over the last decade."
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Sean has been a credit both on and off the pitch, respected by players, staff, supporters, and the wider football community.
This was an incredibly difficult decision, but we feel a change is needed to give the squad the best chance of retaining its status, as results this season have been disappointing.
The process of replacing Sean has begun and further announcements will be made to supporters.
The assistant manager, first-team coach, and goalkeeping coach are no longer with the club.