ActionAid's offers 26 'virtual gifts', in the form of e-cards and pop-up cards, priced from £6 to £75.
Purchasing these can provide various care packages including help for families affected by HIV to funding beehive projects to enable communities to produce food.
Greenlight will be working to enhance Gifts in Action's pay-per-click offering and increasing visibility throughout the Christmas period.
Speaking about the campaign ActionAid marketing manager Peter de Vana Franks said: "Behind Greenlight’s paid search service is a division of talented people and proprietary systems and processes, geared up to routinely outperform mainstream tools and agencies.
"We are confident the combination of Greenlight’s expertise and technology, will contribute to significantly driving our ‘Gifts in Action’ online campaign at a market leading level of efficiency, helping us succeed in achieving the results we want."