The company has tasked Flourish with developing monthly campaigns intended to encourage renewals from holders of its motor and home-insurance policies.
The agency has handled customer acquisition for the German-owned insurance firm's products in these two sectors since January 2004.
The customer retention business was previously held by agency Red Tag.
The appointment was made by Sharon Kellett, direct marketing manager at Allianz Cornhill in a bid to streamline the agency roster.
The insurer operates the Cornhill and Cornhill Direct brands in the UK.
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