Senior executives of the Suffolk-based brewer are understood to be in discussions with a number of London shops before drawing up a shortlist of four contenders who will be invited to present strategic recommendations.
The agency search is part of the company's declared aim to become one of the top ten ale brands during the next three years.
Last year, the company redesigned its packaged beers, including Adnams Suffolk Strong Bitter and Adnams Broadside, and announced new listings with major multiples including First Quench, Tesco, Waitrose and Safeway.
The company's marketing strategy has traditionally highlighted its Suffolk roots. A regional TV campaign launched in 2001 featured the line "Southwold, by the pint".