Academy director Nick Marshall, finance director and company secretary John Pelling, operations manager Brandon Furse and media and communications manager Fraser Nicholson have all left the club.
Marshall and Nicholson had both been at Forest for 16 years, while Pelling and Furse had been employees at the City Ground for 14 and 12 years, respectively.
The sackings continue the ongoing backroom changes at the club, which has seen CEO Mark Arthur, head of recruitment Keith Burt, and former chairman Frank Clark, who was acting as an ambassador for the club, all leave in recent weeks.
Last Wednesday, Forest's Kuwaiti owners brough Billy Davies back to the club for a second spell as boss, becoming the fourth manager to work under the Al Hasawi family since they took over the club in July.
On Wednesday, Wolves and Blackburn coach Bobby Downes was appointed as the club's new head of recruitment, replacing Burt.