She will work at the EDC-backed digital agency on clients including William Hill and Bacardi. She joins the newly appointed executive creative director, and fellow former LBi creative, Laura Jordan Bambach.
Hamrén, a conceptual creative at LBi since September 2010, was promoted to the position of associate creative director in February.. She worked on the development of DigitasLBi’s unicorn branding.
She has worked on brands including Sony Mobile, The Guardian and Macmillan Cancer Support.
Jordan Bambach said: "Thea is an exceptionally gifted creative. A rare talent who can put her hand to anything, from beautiful storytelling to events to cutting-edge technology."