Paton, who was appointed MD at Henry's House in 2003 before the agency rebranded to House PR in 2009, said she was leaving to "embrace new challenges".
Paton said: "The sale of House to the W Group has already been a big success. I leave the company in rude health and with a fantastic future ahead. The time is right for me to move on and embrace new challenges and I am relishing the prospect."
Before joining Henry's House, Paton was board director at Jackie Cooper PR between 1997 and 2003, her LinkedIn profile states.
Paton is also a mentor in the Women in PR/PRWeek Mentoring Scheme, the project that aims to inspire the next generation of female PR leaders.
Warren Johnson, founder and CEO of the W Group, said: "We are grateful to Ginny for her steady stewardship during the 12-month transition, and wish her every success in the future. We look forward to seeing House continue to grow and prosper under its new leadership and with a first-rate team on board."
House PR, which was acquired by W last year, has clients including Ask Italian, London Art Week, and Countryfile Live on its roster.