Iris beat McCann, VCCP and the incumbent, MWO, in a process led by Will Hamilton, the managing partner at Hamilton Associates.
As Wickes’ lead strategic and creative agency, Iris will be charged with developing a new multimedia "platform" and expand the retailer’s share of the inexperienced DIY market, which is dominated by B&Q and Homebase.
The brand’s existing advertising uses the strapline "It’s got our name on it" and is aimed at those proficient in DIY.
Matthew Gaunt, the head of brand communications at Wickes, said: "Strategically and creatively, Iris is the right fit for us and we were consistently impressed by the way they approached our brief and brought our vision to life."
Carat will continue to handle Wickes’ media planning and buying account, and Weber Shandwick its PR.
Dan Saxby, the chief executive of Iris, said: "With the team at Wickes, we believe we can deliver breakthrough work and a transformational partnership."