A High Court ruling means that the supermarket giant can start building an 80,000 sq ft store at Meols Cop Retail Park more than five years after plans for the scheme were first submitted.
A judicial review bidding to prevent the development going ahead was brought by “an independent third party local to the town”, according to Sefton Council.
However, following the High Court ruling, construction work on the new Southport store can now begin.
The supermarket will be built on the site of the vacant former Homebase unit at the retail park.
A spokesperson for Sefton Council said: “We are pleased that a High Court ruling has found in favour of planning permission being granted for the creation of a Sainsbury’s superstore in Meols Cop, Southport.
“This decision to find in favour of the council’s initial judgement is warmly welcomed and reiterates the extensive discussions, analysis and due diligence conducted by Sefton’s planning team throughout this process.”
Before the judicial review, both the council and the Secretary of State had backed the plans twice.
In 2016, plans for a 120,000 sq ft store were passed but work never started on site.
Two years later, landlord UBS Global Asset Management and Sainsbury’s then lodged refreshed plans for a smaller store, which were also approved.
Among those that opposed the project were Lib Dem councillor John Pugh, who endorsed a petition against the scheme that said a new supermarket was unnecessary as the area was already well served.
The creation of a new Sainsbury’s store at Meols Cop is subject to the Southport’s Lord Street branch remaining open for five years after the new supermarket opens.
Sefton Council said: “Should Lord Street close before that five-year period, it would then mean there can be no further trading from the Meols Cop store.
“This precaution is covered by a legal agreement as we continue to help safeguard the continued health and regeneration of Southport town centre.”
Hadfield Cawkwell Davidson is the architect for the project and Savills is the planning consultant.