Matt Posser has been chosen as the new shared chief executive for the Dorset tri-council partnership.
The appointment is the first stage in amalgamating the three districts into a single administrative organisation with a joint management team, as proposed earlier this month.
Mr Prosser, who is currently chief executive of West Dorset DC and Weymouth and Portland BC, is set to take on North Dorset DC as well, pending approval of the full council later this month.
A full council meeting will be held on 19 February which will finalise the appointment.