The company said the appointment would not affect its relationship with local agencies. In the UK, the Miller media account is held by Havas-owned Media Planning Group.
MEC Global Solutions has been given a brief to work with SABMiller's operating companies around the world, to improve brand communications planning. The role will be primarily to train and mentor staff.
Charlie Hiscocks, brand communications director for SABMiller, said: "We have been working with MEC for some time and they have been massively helpful in raising the standards of our communications planning.
"As communications become increasingly complex, we need to challenge ourselves to make sure that we are investing every dollar, rand, euro or pound in the most productive way."
Jim Taylor, regional director of retail for the EMEA region at Mediaedge:cia, will head the account. He has already worked with SABMiller in the past.