Curtis replaces Richard Jukes, who became chairman as part of the reshuffle announced last month.
Curtis was formerly a director in Grayling’s public affairs team and has over 10 years’ consultancy experience. In his new role, he will be responsible for the day to day running of the public affairs team and will continue to work with Jukes.
Jukes said:"I’ve worked with Jonathan for a number of years and he is a huge asset to the company and our clients. I am delighted that he has agreed to take on this role and I look forward to working with him closely as we continue to grow the public affairs business across our network."
Curtis said: "This is a hugely exciting time to be heading up the public affairs team at Grayling. I’m delighted to be taking on this new role and will be working with our talented team to deliver results for clients while pursuing some great new prospects."
The management reshuffle announced in mid-June also saw global engagement leader Sarah Scholefield made MD for the UK and finance director Sam Williams promoted to chief operating officer.
Speaking to PRWeek at the time, Clarke said she "doesn't have a masterplan" about her next career move but would stay in PR.