The book, 'A Simples Life, My Life & Times', which outlines the life and times of the aristocratic meerkat, had topped the Bookseller list, with more than 130,000 copies sold.
It has now slipped slightly and sits at number three in the chart for the week ending 4 December, and number six in Amazon's list.
The Bookseller chart lists only Jamie Oliver's 30 Minute Meals and the Guinness Book of Records higher.
Created by VCCP, the meerkat has been a huge success for comparethemarket.com, prompting its competitors to look at new ideas.
A pop-up shop was opened to support the book launch in October, and the book topped Amazon's bestseller list on pre-sales alone.
ZenithOptimedia handle the media buying and LBi handles the digital account.