The US-based company entered the UK last year and has appointed UM London ahead of a multimedia campaign that will use targeted print advertorials and advertising, digital display and cross-media partnerships.
UM London was appointed to the business without a pitch. There was no incumbent, as Tria Beauty has not had a UK planning and buying agency before.
All creative will initially be made in-house by Tria Beauty's US-based team.
Richard Glover, vice-president and general manager for Europe at Tria Beauty, said: "We are very pleased to have UM on board. They have the experience of delivering highly successful campaigns for premium brands, and we look forward to the future relationship in the UK."
Glover confirmed Tria Beauty will spend around £1m on media over the next year. The first work planned and bought by UM London will be print ads due to break in June.
Russell Place, chief strategy officer at UM London, said: "It's great to work with an ambitious, challenger brand like Tria and help it meet its growth objectives in the UK."
Recent work by Interpublic-owned UM London has included a campaign for the Eden Project's Big Jubilee lunch, a brief it picked up earlier this year alongside sister ad shop McCann Erikson.
Follow Maisie McCabe on Twitter @MaisieMcCabe