He takes up his new role of regional director Latin American in July, replacing Otavio Bocchino, who is joining rival media-buying network Universal McCann to be executive vice-president and regional director for Latin America.
MediaCom, a unit of Grey Global Group, has not confirmed Bruner's replacement.
Bruner joined MediaCom in the US in 1986 and has worked on accounts such as Procter & Gamble and Kraft General Foods. He moved to MediaCom Europe in 1990 and established corporate offices in several European countries, including Spain, Portugal and Switzerland, taking up the regional director role in 1996.
Last week, MediaCom scooped the £120m consolidated Masterfoods account, after a pitch against fellow incumbents Starcom MediaVest Group and PHD, as well as Zenith Optimedia Group and Media Planning Group. The company has global billings of $11bn (£7.5bn) and offices in 67 countries.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .