Former Carlisle, Bristol City and Swindon midfielder Peacock has been at the club since 2012 and played a significant role in the club`s promotion to the National League.
After retiring from playing, Peacock took on an off-the field role as head of youth development.
He oversaw Eastleigh`s successful scholarship scheme where several players have gone on to gain a first-team contract.
Forty-year-old Peacock, who had also been turning out occasionally for Graham Rix`s AFC Portchester side in the Sydenhams Football League (Wessex), will be joining Swindon as their new of head of coaching.