Integrated agency ONE won the work with charity Services Sound and Vision Corporation (SSVC) following a three-way pitch.
SSVC currently holds the contract for the Ministry of Defence's British Forces Broadcasting Service, which provides radio and TV to military bases both in the UK and overseas.
The Ministry of Defence is putting the contract out to Europe-wide tender in 2011. The agency has been brought in to raise brand awareness in advance of the tender.
It will also raise the profile of the charity's other services, which include putting on films, comedy and live music at overseas bases.
The agency will be targeting military communities through the armed forces press such as Defence Focus and online army websites.