Previously Harrison has held senior PR roles at Standard & Poor's and Grayling, where she was director of financial and professional services.
In her new role as client director at Elephant, Harrison will work alongside founder Guy Bellamy and client directors Rebecca Ellis Owen, Paul Bellamy and Nicky Brooke.
Harrison said: "Elephant is an exciting business that is unlike the traditional agencies and as such is attracting well known brands. In my view it is an industry disruptor that challenges the existing PR model. There are no practice or sector silos at Elephant, which ensures clients benefit at all time from all services and skills in single, integrated programmes. Further, Elephant’s broader community investment programme gives the firm a real soul and a social relevance. For me this is a game-changing firm and it’s something I am proud to be a part of."
Elephant founder Guy Bellamy added: "Since launch we have been committed to offering clients the twin benefits of hands-on senior consultants from a low overhead business model. We are going through an exciting growth phase at Elephant and Sophia is a great fit for our culture and our service offer."
Harrison’s move to Elephant follows the arrivals of Al Brenninkmeijer who has launched the agency's film department, account executive Holly Calvert and director Paul Bellamy, who runs the consultancy’s digital and design practice.