The agency beat TBWA\London, Bartle Bogle Hegarty and Chick Smith Trott to the business. The pitch was handled by COI.
AMV will be briefed to develop a campaign promoting the CMEC's Child Maintenance Options service.
The service has been set up to offer impartial information and support for separated families to help parents make more informed choices about child maintenance.
Less than 50 per cent of children whose parents do not live together benefit from effective maintenance arrangements, whether through the statutory service provided by the Child Support Agency or private arrangements.
Justin Chamberlain, the marketing director of the CMEC, said: "The campaign will initially target the 300,000 or so families with children who separate in Britain every year."