The new Whistle board will include Claire Gething, who has been promoted to director, and Whistle's previous chairman Matt Fleming, who will be a minority shareholder and non-executive director.
Whistle was set up in 2012 as part of the Emerge Group, the Dorset-based company that also owns creative agency Thinking Juice, data specialist Refreshed Direct, and media planning and buying agencies Adgenda and EG Media.
Whistle employs 11 people and claims annual fee income of close to £1m. It specialises in PR, digital comms, community engagement and internal comms, with clients including CALA Homes, Aggregate Industries, Churchill Retirement Living and the Glen Dimplex Group.
Kent said: "Over the past three years, Whistle has gone from a start-up to a £1m company with a strong culture, great team and a solid client base. This feels like the natural next step for the company, with continuity of culture and management as we start a new chapter.
"We have exciting plans for the business that will see us grow the team, build on specialist areas and introduce some new services. However, our core focus will remain on adding commercial value to our clients through strategic consultancy, creativity and exceptional client service."