Communities secretary Sajid Javid has said he would approve a reorganisation proposal under which unitaries Bournemouth and Poole - with Christchurch district - would form a single unitary council.
Another unitary would cover the rest of Dorset: East Dorset, North Dorset, Purbeck, West Dorset and Weymouth & Portland, with the present county council being abolished.
Proponents of the change have said it will yield efficiency savings of more than £100m over six years.
East Dorset, Purbeck and Christchurch originally opposed the reorganisation but the former two dropped their objections last month, leaving Christchurch alone in its resistance.
A joint statement issued by the leaders of the other councils involved said: “This is an historic day for public services in Dorset. Now we have received this decision, we can collectively focus our efforts, through the established joint committees, on creating two brand new councils.
“Our strong track record of partnership working in Dorset, whether through shared chief executives and management teams or joint service delivery, demonstrates our ability to put in place creative and innovative ways of working, and shows we will always put the provision and preservation of essential frontline public services and the interests of our residents first. “
But Christchurch deputy leader Trish Jamieson said she was disappointed by Javid’s decision as in a local poll 84% of local residents had opposed Christchurch being merged with its neighbours.
She said: “We will be calling an extraordinary full council meeting to allow us to consider our position moving forward and the opinion of the legal professional as to whether there is any arguable error in law.”
Dorset MPs also welcomed Javid’s decision, with the notable exception of Christchurch’s Christopher Chope.
A joint statement by the other seven MPs said: “Given the pressures on public spending, the only affordable way to meet the needs of the elderly, the young and the working population is to reduce unnecessary overheads and to streamline service delivery.
“These proposals will make such innovation and efficiency possible by replacing our current nine councils with just two new single tier councils - a massive reduction in bureaucracy.”
In a parliamentary statement, communities secretary Sajid Javid said: “Having carefully considered all the representations I have received and all the relevant information available to me, I…have decided to implement, subject to Parliamentary approval, that locally-led proposal to replace the existing nine councils across Dorset.”
He added: “I am satisfied that these new councils are likely to improve local government and service delivery in their areas, generating savings, increasing financial resilience, facilitating a more strategic and holistic approach to planning and housing challenges, and sustaining good local services.”
The new council would take effect on 1 April 2019, Javid said.
