Grayling Engage will offer help on consulting with stakeholders and the public.
The unit is being led by Hannah Wynne, engagement and consultant director. She has moved from 3G, where she was community relations and consultation manager.
Wynne said: 'With councils transforming services, the NHS reconfiguring to improve clinical outcomes and the private sector continuing to invest in major infrastructure and housing programmes, effective public consultation is becoming more important, especially as "no" campaigns become more sophisticated.'
She will report to James Ford, head of the public sector, health and skills team at the agency.