Avenue counts Servier as one of its clients, although the agency works for its UK operation as opposed to its international HQ.
Carroll co-founded CPR 12 years ago but had been working for the agency, part of Fleishman-Hillard since 1999, as a freelance after stepping down from a full-time role in April. His final day with F-H was last Friday.
At Avenue, Carroll reports to CEO Jeff Smith.
Carroll recruited Smith, a US national, to an account director role at CPR seven years ago. Smith later moved on to Lilly UK before joining Avenue owner Huntsworth, and then Avenue, last year.
Carroll acknowledged his exit from F-H was 'the end of an era' in respect of the fact that former CPR heavy-hitters have all moved on from F-H.
Carroll co-founded CPR with Scott Clark and Moira Gitsham in 1993. The latter duo quit last year and have since set up Tonic Life
Communications with Oliver Parsons, the former CPR Worldwide MD.