Equi=Media, which specialises in direct and digital media, has been tasked with redesigning Esure's sites, maximising conversion rates and improving return on investment across all digital budgets.
The company's websites also include First Alternative and Halifax Car Insurance. Equi=media already handles Esure's digital media planning and buying account.
Ryan Webb, director of projects at Equi=Media, said: "We are very excited to have expanded our work with esure to include website design and architecture specifications on top of the existing online and offline media planning and buying.
"The esure brands already experience huge success in attracting consumers to their sites but we will be working together to ensure that this traffic is effectively converted into further financial success for the group."
Chris Bowden, head of marketing at esure, said: "Most of our marketing communications drive consumers to our brands' websites.
"Therefore it is imperative that users have easy access to information and enjoy a positive brand experience."