MacDonald will report to the McCann chief executive, Stephen Whyte, when he arrives at the end of the month. His arrival follows the departure of the managing director, Nick Wright, from the agency at the end of last year.
The move reunites MacDonald with the McCann executive creative director and founder of RKCR/Y&R, Robert Campbell, who joined McCann a year ago.
MacDonald has worked at RKCR/Y&R since 2000. He joined as the managing partner, running Lloyds TSB, Virgin Mobile, Schweppes and News International, and was promoted to managing partner for business and commercial development in 2003.
Before RKCR/Y&R, he worked at Publicis on accounts including Coca-Cola UK. He previously worked at Lowe Howard-Spink on Vauxhall Motors. His career began in 1993 at DMB&B as a graduate trainee.
Whyte said: "Chris has extraordinary energy, a real passion for advertising and the ability to motivate and lead. We are delighted that he's joining us."