McDonald replaces Ivan Ali-Khan, who is joining Flextech in the New Year as its head of media planning.
McDonald moves to MPG two months after the closure of The Allmond Partnership, where he was the commercial director and managing partner. Previously, he was the sales director at GMTV and also worked for PHD and Abbott Mead Vickers BBDO as its broadcast controller.
The move is the latest in a series of senior appointments at the Havas-owned media agency since Mark Craze joined as its managing partner in July to work alongside Marc Mendoza.
Craze said the hiring marked an important step in their three-year development plan for MPG: "We want to work in collaboration with the media owners to deliver cut-through ideas for our clients and a key part of McDonald's remit will be to do this."
McDonald, who will join the agency in December, said: "There is an entrepreneurial spirit at MPG and I am excited to join the agency at this stage of its development."