Tin Man's appointment follows a competitive pitch that began in April.
Cirkle's remit is to deliver a six-figure consumer press office, alongside the agency's current b2b brief, awarded last year, which spans seven brands.
The two new agencies join long-term agency partners Red Consultancy, which is retained on the Robinsons, Purdey’s, Aqua Libra and Fruit Shoot brands; and Splendid Communications, which is retained on The London Essence Company, Monte Rosso and Thomas & Evans No.1.
Davnet Doran, acting head of brand PR at Britvic, said: "We have incredible iconic and innovative brands and we are very happy to have the best selection of consumer agency partners support us with strategic, smart and impactful stand-out brand campaigns and always on press office."
Mandy Sharp, founder of Tin Man, said: "We’re super excited about the opportunity to work across some of Britain’s best-loved soft drink products. Our first campaign for J2O Spritz is contemporary, cheeky and irreverent, and we’re confident will find a place in our target consumers’ heads and hearts this summer."
Cirkle MD Ruth Kieran said: "We’re proud to be working alongside such a strong roster of agencies as we support Britvic and its iconic brand portfolio in the quest to hydrate the nation."
Tin Man has created a tongue-in-cheek campaign for J2O that ribs the trend for overpriced and pompous mocktails.
The Mocktail Madness campaign features a series of short films contrasting the over-the-top and outrageous nature of the mocktail to the simplicity of a J2O Spritz. The campaign is supported with a media relations programme looking at the often bizarre, modern day food and drink trends sweeping the country.