The move will see Grayling’s Brands team move to Atomic, which will become a 25-strong group led by Atomic MD Daniel Cohen, whose new role is to be global head of brands at Grayling.
Parent company Huntsworth said there would be no redundancies associated with the merger, despite recent rumours of redundancies in Grayling’s consumer/brand practice.
Huntsworth said the merger was "a result of a wide-ranging strategic review of the Grayling business in the UK".
Sarah Scholefield, MD Grayling UK & Ireland, said: "The merger signals Grayling’s commitment to delivering high impact, content-rich campaigns for brands across our network of eight UK offices, as well as globally. Daniel’s pedigree in leading award-winning campaigns makes him ideal to spearhead the future growth of integrated brand communications work with the newly merged team."
Grayling has experienced difficult trading in recent months. In the first half of 2015, like-for-like revenue across Huntsworth fell 0.7 per cent, with a decline of 8.8 per cent at Grayling.
Earlier this year, Huntsworth said it had closed five Grayling offices globally as part of a wide-ranging restructure under new CEO Paul Taaffe. Grayling UK CEO Alison Clarke left in the summer.
Cohen has worked for Huntsworth for more than 10 years, initially running the consumer business for Harrison Cowley, then spearheading Trimedia before joining Atomic in 2012.