The review comes as part of a major overhaul of the brand's marketing strategy, which is being implemented by William Hill's new group brand and marketing director Kristof Fahy.
The Brooklyn Brothers will not repitch for the business.
Fahy joined the bookmaker from Yahoo! at the end of November last year, just weeks after The Brooklyn Brothers was appointed to the account.
The agency had picked up the business following a pitch against Miles Calcraft Briginshaw Duffy.
Alex O'Shaughnessy, William Hill's head of product and marketing communications, handled the process.
Previous to the appointment, William Hill had used an in-house marketing team to create the majority of its ads. It had also worked with the Manchester-based agency BJL on a project basis.