Radiator will handle the PR, celebrity seeding and the development of a social media campaign for 2015 for the company as it looks to grow in the UK.
The agency said its focus would be on telling the Ipanema story and raising product awareness.
Mason Young, marketing and PR manager at GH Warner, the UK distributor for Ipanema, said: "We chose Radiator on the strength of its approach – looking at our brand overall and creating a combined PR and social road map for 2015."
Radiator co-founder Gaby Jesson said: "Ipanema is such an exciting brand to be working with this year. Its product range and back story gives us so much to work with and we are very excited to be working on an exclusive celebrity-led social campaign that we will be launching later in the year."