Iris will handle brand strategy, creative development and activation activity for the year.
This will include above and below-the-line elements to help generate trial among new Fetzer consumers as well as encouraging existing customers to buy more frequently.
Iris will launch an integrated campaign this spring targeting "earth friendly enthusiasts" and premium wine drinkers through press ads, digital, retail activation and sales promotion.
Fetzer, a range of Californian wines, is one of two ethically focused brands under the Brown-Forman umbrella, the other being Bonterra Vineyards.
Iris already works for a number of brands in the Brown-Forman portfolio including Jack Daniel's, Southern Comfort and Finlandia Vodka.
Steve Bell, CEO of Iris London, said: "We've been working with Brown-Forman brands for over five years now and we're delighted to be extending our relationship once again with the appointment of Fetzer and look forward to producing some stand out campaigns for a brand that is leading the way in sustainability."
Georgia Chubb, brand manager for Fetzer in the UK, said: "We were lucky enough to receive some excellent pitches for this campaign, but in the end Iris' strategic thinking and creative expertise won out.
"We loved their innovative suggestions on how to bring Fetzer's earth-friendly credentials to life in a crowded marketplace, and can't wait to see the activities unfold in the year ahead."
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