Called SO What Global, it will be an umbrella company for several specialist agencies. Initially this will include SO Talented, a "hybrid" agency combining talent recruitment and reputation consultancy.
Another agency is SO Active, a sports marketing consultancy with Dawson as a founding partner. The agency will focus on consumer behaviour change through sport.
"Having Matt as part of our team is tremendous," said Clark, group CEO of SO What Global.
"Matt offers a wealth of insight from his career and relationships in world of sport, as well as a keen sense of what makes a successful business. He also has a passion for helping people to improve their health and lifestyle.
"In the future, SO will look for opportunities to expand its portfolio even further into other enterprise-specific sectors and geographies."
Clark told PRWeek: "Our background has been in PR over the years – we made our names in the healthcare sector, and along the way worked with a number of global brands.
"PR is in our DNA but it’s not the only thing we’ll be doing in this new offering."
Clark said he expected to be able to announce the venture’s first clients in the coming weeks. A number of appointments are also set to be made, including managing director of SO Active. The agency’s office is in Horseferry Road, off Millbank in London.
Tonic Life, which was founded by Parsons and Clark but is now owned by Huntsworth, is a specialist health agency and Clark said SO What Global would not look to undertake healthcare PR because of conflictions with that agency.