The agency won the business after a pitch against Proximity London, Partners Andrews Aldridge, DraftFCB and Kitcatt Nohr Digitas.
Between 20 and 30 shops were initially invited to a briefing before 15 were shortlisted. Five were eventually invited to the pitch for the account.
The DH previously used agencies including Partners Andrews Aldridge, CMW, EHS 4D, Iris and Kitcatt Nohr Digitas across its direct marketing and digital accounts.
The decision to consolidate into OgilvyOne is part of the department's efforts to create efficiencies in a bid to make it "easier" to get its message across.
OgilvyOne will now handle the direct and digital activity across initiatives including the high-profile Change4Life campaign and a dementia awareness drive.
In September, the DH retained Dare and Now, as part of Team EDC, to handle the ad account for its high-profile anti-smoking campaign. The agencies beat McCann London, Mother, DLKW Lowe, M&C Saatchi and Wieden & Kennedy to the business.
Separately, the Government Procurement Service's review of its communications frameworks is ongoing. A decision on the creative services element is due in December.Follow @SaraKimberley