The agency, which had held the account for just under a year, told PRWeek it was Iceland's third consumer PR agency in two years. 3 Monkeys Zeno did repitch for the business, but was unsuccessful, a spokeswoman confirmed.
Agency MD Christine Jewell said: "We were surprised at the repitch being called, especially as we had increased both the quality and quantity of results, and improved [Iceland's] share of voice very significantly during our time working on their behalf. We wish them well with their new PR partner and look forward to using our skills and contacts to the advantage of other retailers."
Iceland PR and product manager Marie Hughes told PRWeek the pitch process was already in the "later stages".
Hughes said: "I'd imagine the successful agency will be announced over the next couple of weeks - at which time we will have scoped more fully what the agency will be tasked with [doing]."
Iceland also works with sole operator Keith Hann, who handles corporate PR, while memorable social media work - such as when its namesake Iceland (the country) performed strongly at Euro 2016 - was carried out by Tangerine.
The supermarket, which on Monday 5 June delivered its end-of-year financial results for the 52 weeks up 24 March, recorded sales of £2.79bn in 2017, up from £2.65bn in 2016.
In 2015 Iceland launched a number of strategic initiatives designed to "differentiate the brand, change consumer perceptions and restore growth to [the] business", said Iceland founder Malcolm Walker in the results statement.
He said: "All our initiatives were successfully communicated through our distinctive 'Power of Frozen' marketing and PR campaign [see below], across both traditional and social media, which is playing a significant role in changing public attitudes to frozen food, increasing appreciation of its many advantages, and identifying Iceland as the natural place to buy it."