MindShare will measure, optimise, track and course-correct the fast-food giant's £31 million UK media and marketing spend.
MindShare ATG, a specialised division, was appointed as McDonald's marketing measurement partner in the UK after a pitch against undisclosed agencies. The business already performs similar duties for McDonald's in Europe and Asia.
Steve Simpson, the global director of MindShare ATG, said: "OMD have been very supportive of our assignment. I don't see it as evaluating OMD's work, but as working in partnership with OMD and helping them do the best job it can.
"We are excited to be working with the McDonald's team and OMD to form a partnership that will out-think and outperform the competition."
James Rennie, the head of marketing at McDonald's, said: "ATG demonstrated proven and relevant consulting and analytical skills, and we are confident that they are the ideal partner for measuring and maximising our return on marketing and media investment in the UK."