Called The Garden, it will aim to provide a "talent management" recruitment service for the creative communications industry, seeking out the best creative facilitators and gifted account people at all levels.
The agency aims to help bring together creative people across all disciplines, including advertising, sales promotion, digital and marketing, with the exception of media planning and buying.
Rapley said: "It is our aim to nurture and develop relationships with talented individuals and then introduce them to the right people at the right time in their careers."
Rapley spent 20 years at the agency before quitting as the deputy managing director to become a director at Claydon Heeley Jones Mason.
In 2002, with the former Grey Worldwide London chief executive Martin Smith, and Roisin Robothan-Jones, he launched Rapley Smith & Jones. The agency was "mothballed" after less than a year.
Parker left DDB to become the managing director of the digital agency Tribal, ending a 17-year stint, during which time she ran the Volkswagen account.
Parker said: "We aim to find and represent only those people who can make a significant contribution to the creativity of their organisation."