The agency won the account after a competitive pitch against two undisclosed agencies.
HMDG will focus on driving awareness and attracting new consumers who have an interest in healthy eating and an appreciation of quality food values.
Steve Clarke, Rachel’s Dairy marketing director, said: "HMDG really demonstrated that it understands the brand’s potential and where it could go. We’re very pleased to have them on board as our new partner."
Zenith is the incumbent media agency and Haygarth leads the CRM and digital activity. Both agencies are unaffected by the appointment.