The Ballymena operation, famous for building London buses, was placed into administration last month with the loss of 1,200 jobs.
The former business owner Jeff Wright is a pastor at Green Pastures Church and came under fire after the church received £15 million in donations from the firm when it was profitable.
English industrialist Jo Bamford announced on Friday that he had agreed a deal in principle to buy the factory and associated land from Wright.
There was jubilation among former workers at the gates of the plant on Friday morning as the news emerged.
Steve McMaster, who has worked for Wrightbus for 42 years, described it the best day in his time working for the firm, and vowed it will "once again be the best bus company in the world".
But regional officer for the Unite union George Brash warned that, while a deal has been agreed in principle, there remain "a few hurdles to get over".
"We are hopeful there will be some formal deal by Tuesday next week," he said.
"Workers have been through the mill for the last two weeks so they are entitled to a bit of euphoria.
"It is good news but ... we want to see that in writing and then get to the next stage and see how many people will get employed."
Work is understood to be continuing across the weekend, and workers will be briefed on developments on Monday at a meeting at Ballymena Showgrounds.
Northern Ireland Secretary Julian Smith tweeted his congratulations to those involved.
"Hoping to see this get over the line in the coming days," he said.
North Antrim MP Ian Paisley welcomed the developments.
"I am delighted that, after asking Jo Bamford to consider Ballymena as a location for a significant business investment, this has resulted in this deal," he said.
Traditional Unionist Voice (TUV) leader Jim Allister also commended those involved.
"It's a wonderful opportunity now to put back to work all these fantastic workers to rebuild this world-leading industry and to make this factory great again," he said.
A dispute over the sale of assets had been the sticking point preventing an overall purchase of the business.
While the company is in the hands of the administrators, the factory and associated land are still controlled by Mr Wright.
Mr Bamford and Mr Wright were at loggerheads over the asset sale, a stand-off that had put the sale of the Wrightbus operation in jeopardy.
On Friday, the men announced the resolution of that issue.
Mr Bamford, who is the son of JCB chairman Lord Bamford, expressed hope that he could now complete the overall purchase with administrators Deloitte.
"We are delighted to announce that this morning I have agreed terms on a deal in principle with the Wright family for the Wrightbus factory and land," he said.
"We are still to conclude a deal with the administrators but are pleased to report this important step in the right direction."
Mr Bamford thanked Mr Paisley for helping to mediate what he described as a "tricky negotiation".
A statement from Mr Wright's representative confirmed the deal.
"Following intensive overnight negotiations between the two parties, agreement has been reached in principle over the sale of Wrightbus to Ryse Hydrogen (Mr Bamford's company)," it said.
"The two men at the centre of the deal, Jeff Wright and Jo Bamford, say the outcome of the negotiations involved pragmatism in arriving at an arrangement which is ultimately in the best interests of the long-term sustainability of the bus manufacturing business and jobs in the Ballymena area."
Farmland close to the factory premises had been at the heart of the dispute.
Mr Wright said that, as part of the deal, he had agreed to give the farmland to Mid and East Antrim Council to acknowledge the contribution of Ballymena people to the Wrightbus brand over 70 years.
"This legacy gift is a tribute not only to my father, his father before him, and the Wright family members, but most importantly it is a tribute to the generations of workers who helped build a proud manufacturing tradition in Ballymena," he said.
Mr Wright said the council had confirmed the land would be used for a proposed innovation centre for manufacturing start-up companies.
"The Mid and East Antrim Borough Council estimates that the legacy of the site and the new investment would result in 2,460 jobs with the potential to rebuild Ballymena.
"It is also has ambitious plans to secure one of the Heathrow Hubs for the town, which would see a further 5,000 engineering and manufacturing jobs for the area.
"The new innovative Hubs are to be used to pre-assemble components of the expanded airport before transporting them to Heathrow."
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