The agency will be tasked with reviving the brand that has seen sales fall dramatically in recent years since the brand’s initial success.
The Group recently reported revenue for the six months to 31 August decreased 10.5% to € 257.5m (£237m).
As a result of the sales dip, and the recent acquisition of the Tennent’s brand, the company said it was going to reassess the planned £8m it announced it was to invest in the brand in July.
C&C Group has made several moves this year to revive flagging sales.
In August, it bought Anheuser-Busch InBev’s Irish, Northern Irish and Scottish businesses, including the Tennent’s brand, in a bid to establish Magners in those countries.
The company also called a review of the Magners advertising account, currently handled by Euro RSCG London and the agency network’s Dublin office Young Euro RSCG.
The group has since launched a new Pear variant supported by two campaigns featuring comedian Mark Watson.
The company called a review in August. The account was previously handled by Young Euro RSCG, which it is understood will continue to handle the Irish account.