Wild Card won the work following a competitive pitch. The contract is ongoing.
The agency will provide press office support to the group's brands, which include New Covent Garden Soup, Linda McCartney, Love Tub and Farmhouse Fare.
Emma Sykes, head of corporate comms at Hain Daniels Group, said: "Wild Card has extensive and impressive credentials across the food industry, and we are looking forward to our own brands benefiting from the consultancy’s depth of expertise and network."
Tessa Willmott, managing director at Wild Card, added: "The group's diverse portfolio really does offer something for everyone and we can't wait to get started. This win is a culmination of a great first half year for Wild Card, where we have seen businesses such as Whitby Seafoods, Kallo, Thomas J Fudge’s, Weight Watchers and Highland Spring join the fold."
Earlier this month, Wild Card won a one-year contract to run a campaign for Linda McCartney, and at the start of this year the firm announced internal promotions to MD and CEO level.