The pitch process was handled by the AAR. The business was previously handled in-house.
M.i. Media will work on new product development campaigns as well as emergency appeals.
Virginie Kan, the UK head of supporter acquisition and marketing at ActionAid said: "After an extensive search process, M.i. Media were the agency that best demonstrated how to move the organisation’s fundraising activities on to the next level.
"In the short period we have been working together, they have already made a positive impact on our results".