Following the 6-0 League One defeat atBolton, Lee Johnson and his company have parted ways.
The Stadium of Light has lost an assistant head coach in Johnson.
The defeat on Saturday left the Black Cats two points off the top spot in League One.
"I would like to thank Lee for his commitment and effort over the past 14 months," said Louis-Dreyfus.
We regret that we had to make this decision, but felt that change was needed immediately.
We firmly believe that this is in the best interests of the team as they try to get promoted this season.
In 75 games, Johnson won 41 times, including the club&s first Wembley win in 43 years.
Saturday's defeat was their biggest since October of last year, and they have played more games than both the top two and Wigan, who have four matches in hand.
The process to appoint a new head coach will begin immediately and a further update regarding the club's interim coaching set-up will be communicated shortly.
Excluding caretakers, the Wearsiders are looking for their 12th boss in 10 years to follow the line of Martin O'Neill, Paolo Di Canio, Gus Poyet, Dick Advocaat, Sam Alladyce, David Moyes, Simon Grayson, Chris Coleman,