The word of mouth specialist will handle press office, consumer, and trade PR for the company's portfolio, which includes ice lollies Fab, Skinny Cow, and Mivvi.
The account is for 12-months and will kick off this month.
A key part of the campaign will be to create buzz around its 'Design a Fab Den' promotion.
Publicasity previously held the account for four years, and will continue to work with the firm until the end of February.
'A key requirement for us was to find an agency that understands the broader marketing picture and can provide PR expertise to compliment the other disciplines, like advertising, digital and experiential', said Nestle brand manager for R&R Ice Cream James Beaumont. R&R Ice Cream produces the ice lollies under license from Nestle.
Finn Communications is now nine-strong after it recently appointed James Newman as account director and Julia Round as senior account executive. Both were formerly at Ptarmigan, where Newman managed the Diageo and Virgin Media accounts.