Bishboshbash was formed last month to offer event design and production for parties, corporate functions, team-building days and conferences. It already boasts the Evening Standard and Williams F1 as clients.
Parkes founded Richmond Events where she launched the Marketing Forum and the Communication Directors Forum.
Parkinson previously ran Marketing Works where she developed team-building and motivational events for clients including Rothmans International.
Parkes said: "People can come to us for well-thought-through content. We have a list of associates such as audiovisual and logistics firms so we can build the right team for each project."