Sainsbury’s will re-open in Bognor Regis in spring 2013.
The 400-plus staff at the new store will welcome their first customers in about 20 months’ time.
The retailer has pledged to ensure the new jobs will help the town’s economy as much as possible.
Maria Twomey, its spokeswoman, said: “These new jobs will make an important contribution to the future vitality of Bognor and we see this as a major benefit of our scheme.
“Sainsbury’s is delighted the regeneration of the former Lec site is finally under way.
“We are confident this development will make a significant contribution to the wider regeneration of the town.
“We are excited about becoming part of the community of Bognor once again.”
Ms Twomey thanked everyone who had backed the company since its £50m scheme for the former fridge and freezer making factory was revealed in October 2008.
This support was crucial when the planning inspector at the public inquiry called by the government into the plans received an unprecedented 1,000 comments.
She was speaking at a ceremony at the Shripney Road site last Saturday held by its owner, Sime Darby London, to celebrate the start of redevelopment work.
The occasion allowed some 50 guests a last chance to look around buildings which played a pivotal part in Bognor’s working life for some 50 years. More than 2,000 people worked in the factory and offices at their peak.
But the buildings were last occupied in 2003. The first activity on the site since then came when contractors for Sainsbury’s moved in on July 11 to begin to remove asbestos from the derelict buildings.
General demolition and work to clean up the chemical contamination of the site from its original use as a gasworks will take place before the 55,000sq ft store and petrol filling station starts to be built next spring.
Sime Darby London corporate director Raof Daud said: “This is a great day for Bognor and we are delighted to have played our part in helping to facilitate the regeneration of the former Lec site..
“We also thank the local community and stakeholders for the extraordinary level of support we have received.”
He thanked Arun District Council for its help in bringing the site back to life.
Gillian Brown, the council’s leader, said the new store would create an attractive entrance to the town and sent a message large firms were prepared to invest in the town.
“It also brings one of the biggest and most recognised retailing names back to Bognor, something we have been working on for a long, long time,” she said.
There would also be 20,000sq ft of employment space next to the store for new and growing businesses to use as a further benefit of the scheme.
Bognor Regis and Littlehampton MP Nick Gibb said: “The main gateway to Bognor has been blighted in recent years by this derelict site.
“We are are all going to benefit from this store. It will provide much better choice for shoppers and is a sign of a positive future for the town and the area.”