BBH beat Clemmow Hornby Inge, Publicis and the incumbent, Banks Hoggins O'Shea/FCB, to secure the brief. Last year, the company spent £3 million on advertising, but that could rise.
The pitch was called in December as part of a review of the brand in the face of growing competition from Coral and William Hill.
Simon Miller, a former account handler at J. Walter Thompson and Publicis, oversaw the pitch. He confirmed that BBH's appointment meant the company would no longer be working with Banks Hoggins O'Shea. He said the company was considering advertising, but that it would first look at what to do with the Ladbrokes brand.
BBH has previous experience in the betting industry following its work on Ireland's largest bookmaker, Paddy Power. However, that account is now dormant.
Ladbrokes' latest above-the-line activity was a press campaign in January through BHO that featured Wild West images to promote its online poker game.
The bookmaker's media buying business is split between Pure Media and TCS Media. It is not expected to be affected by the review.