It follows a pitch process led by Barclaycard's global brand director Gary Twelvetree and UK marketing director Katherine Whitton.
Iris will focus on delivering ‘innovative and compelling engagement models' to complement the brand's above-the-line work. Other agencies on Barclaycard's roster include Bartle Bogle Hegarty (BBH), Walker Media, Dare and Vital.
‘Iris showed great understanding of what we are looking to achieve in this market, as a leading payment provider, and the exciting challenges ahead,' said Whitton.
Earlier this year, Barclaycard appointed Rapp to handle its new rewards programme, set to launch next year.