The club is the UK's biggest mail order bookseller and is battling to maintain its place against online competition such as Amazon.com.
MediaVest's new account does not include online business, which will continue to be handled by marketing affiliates. The review was led by Nick Rice, director of club marketing at Book Club Associates.
According to The Nielsen Company, the firm spent £4.3m on media in 2008, the bulk of which went on direct mail, handled by Carat Direct.
The appointment follows changes to Book Club Associates' core operation since it was sold by media group Bertelsmann to Aurelius last year.
The company's marketing activity is still expected to revolve around its negative option business model - where subscribers get an initial discount upfront after committing themselves to buy a certain number of books within the year.
The BCA book clubs now handled by MediaVest include World Books, The History Guild, The Softback Preview, Books for Children, The Military & Aviation Book Society, Sci-Fi and Railway.