Leeds-based Poulter Partners was appointed by the group following a undisclosed three-way pitch.
The agency claims that advertising will lead the campaign, which will also use radio, posters and in-store activity.
Kicking off in April, a radio, bus vinyl and poster campaign will highlight offers available in store and this will be backed by door drops and direct mail targeting 100,000 consumers throughout the province.
Poulters claims that the convenience store sector is highly competitive and the aim of the campaign is to build loyalty by offering incentives to shop and news of in store deals. The Co-op already claims the campaign has already been successful elsewhere in the UK.
Elaine Patton, micro-marketing officer from the Co-op, said: "The marketing campaign emphasises our commitment to Northern Ireland consumers."
Earlier this month, Poulters launched a campaign for the National Bingo Game Association to promote bingo's image as a leisure pursuit. It was supported by a £3m advertising and promotional blitz.
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