A North Yorkshire district council chief executive will do the job three days a week and spend the remaining two days working at County Hall.
Mary Weastell is to take over as chief executive of Selby DC upon the retirement of Martin Connor this summer and will also become assistant chief executive (customer services) for North Yorkshire CC.
Ms Weastell, who is currently a strategic director at Bradford MDC, said: ‘I am absolutely delighted to accept this new joint leadership role for two very ambitious councils at the forefront of service innovation and collaborative partnership working.
‘I am looking forward to the challenges ahead, especially the diversity of the job and the ability to further strengthen the partnership at both a strategic and local level to deliver quality services for communities in the place in which I live.'
A county council representative said: ‘The arrangement is aimed at bringing about better customer service, greater resilience for the communities and to open the way for financial savings.
‘At the heart of the plan is recognition of the importance of maintaining the separate sovereignty of each council and its own decision making processes.'