The agency won the account, worth £1m over the next three years, following a five-way pitch.
Among those who also pitched was Edelman, which already handles Birds Eye Walls B2B account. Edelman has also previously handled consumer projects for the firm.
The appointment of Cairns follows a £7.7m relaunch of the Captain Birds Eye brands in the summer.
The agency team, led by Cairns MD Ann Cunnane, reports to Nicki Hickson, marketing communications manager at Birds Eye Wall.
Cairns senior account director Emma Woodgate said that details of the brief are being hammered out this week. This will include consumer PR and a focus on healthcare.
The summer relaunch included an emphasis on healthy eating for the brand with new limits on fat, salt and artificial preservatives.
It also saw the reinstatement in advertising of the traditional fatherly character Captain Birds Eye, who had been replaced by a younger character.
The range of brands that are covered by the brief include Fish Fingers Chicken Nuggets, Chicken Dippers, Captain's Coins and Vegetable Fingers.
Birds Eye Walls is owned by Unilever. The account win extends Cairns' Unilever client list, which includes Unilever Bestfoods' Go Organic pasta sauce and soup range.