Mark was appointed CEO of WPP in September 2018. He has held multiple leadership positions at WPP since joining in 1989, including Head of Strategy and CEO of WPP Digital. In 2015, he became Global CEO of Wunderman.

Earlier in his career, Mark co-founded internet start-up WebRewards and specialised in media and marketing as a principal at consultancy Booz Allen Hamilton. He was recognised as an INvolve Heroes Champion of Women in Business for the fifth consecutive year in 2022 and was named #1 in its Empower Advocates list which recognises leaders who create diverse and inclusive business environments. In 2021 Mark was awarded Fellow of the IPA status for outstanding services to the industry and since 2022 has been Chairman of the Natural History Museum Digital Council.