Derby are currently bottom of the championship table with just one win from eleven attempts this season.
Cocu was appointed as Derby manager in the summer of 2019 after Frank Lampard left for Chelsea and the Dutchman led the club to 10th place in his first season in charge.
The 50-year-old Dutchman has however paid the price for Derby’s poor start this term, with player-manager Wayne Rooney leading a four-man coaching team temporarily until a new manager is appointed.
The Rams are in the middle of a takeover by Abu Dhabi royal family member Sheikh Khaled bin Zayed Al Nehayan, who is the cousin of Manchester City owner Sheikh Mansour.
A statement said: “The club would like to place on record its appreciation for the way Phillip and his staff conducted themselves in what were some extremely challenging situations during his tenure. Phillip and his staff helped develop and establish a considerable number of academy players into the first-team squad and Phillip made significant financial contributions and personal efforts towards the club’s community projects during the Covid-19 pandemic, which the club are extremely grateful for.
“Derby County wishes to thank Phillip, Chris and Twan for their hard work and dedication over the last 16 months and wish them every success in their future careers. The club will provide further updates when appropriate and will be making no further comment in the meantime.”
Rooney said: “I am sorry that Phillip and his staff have left the club and want to thank him personally for all his help and encouragement as part of his coaching staff. The most important thing now is to stabilise the club and start moving up the table. I have been asked to be part of the coaching staff to help the team’s preparations for next Saturday’s vital match against Bristol City. The coaches and I will speak with the players on Monday.”