Jason Gonsalves, a partner at Michaelides & Bednash, will join BBH as its engagement planning director.
Gonsalves will be based at BBH's London office. Brown expects to make similar appointments in other BBH offices globally.
Gonsalves, who joined M&B seven years ago from Universal McCann, works on the agency's Channel 4 business and has been involved in briefs including the broadcaster's award-winning "Indian summer" activity in 2002.
Brown said: "Jason is one of the first in a number of hirings. He comes with good credentials - he comes from a big- agency background at Universal McCann and then moved into media thinking at Michaelides & Bednash. Our aim is to bring high-quality media-channel thinking to the creative process."
Graham Bednash, a founding partner of M&B, said: "Jason is a brilliant man and a fantastic talent. He's been here for more than seven years and wants a new challenge."
Bednash said the agency planned to recruit a senior replacement for Gonsalves who, along with Paul O'Neill, is one of two partners working alongside Bednash and George Michaelides.
BBH hired Brown, a former employee and one of the founders of Soul, last September to launch its engagement planning activity. The aim is for each BBH office in the network to have in-house expertise in the field.