A deal has been reached in principle for the sale of Wrightbus.
Bidder Jo Bamford said agreement had been reached with “the Wright family for the Wrightbus factory and land”.
“We are still to conclude a deal with the administrators but are pleased to report this important step in the right direction.
“I would like to thank Ian Paisley for his hard work and diligence in helping to mediate what has at times been a tricky negotiation.”
George Brash from the Unite union described it as a “momentous day”.
He said it was a tribute to the workforce and the solidarity they have shown.
“There are a lot of smiling faces at the moment,” he added.
“We just need everything confirmed.”
Mr Bamford, an English industrialist, who is the son of JCB chairman Lord Bamford, wants to buy the Wrightbus business and the factory through his Ryse Hydrogen company.
Mr Paisley said he welcomed the announcement by Mr Bamford.
He said Mr Bamford is “concluding the final arrangements with the administrator to take over Wrightbus and get men and women back to work building buses”.
TUV leader and North Antrim MLA Jim Allister said he was “delighted” to hear the news of the deal.
“I want to commend all who made this possible, many working tirelessly behind the scenes,” he added.
“I particularly salute the fortitude of the workers.”
On Thursday, the owner of the Wrightbus factory, Jeff Wright, said he had not been able to reach a deal to sell it to a new owner.
He said that the sticking point had been farmland he did not consider part of the factory site.
A statement from Jeff Wright on Friday confirmed that the farmland will be gifted to the local council as a tribute to his father Sir William Wright.
There are also plans for an innovation centre for start-ups.
“This legacy gift is a tribute not only to my father, his father before him, and the Wright family members, but most importantly is a tribute to the generations of workers who helped build a proud manufacturing tradition in Ballymena,” he added.
“It is my true wish to see this legacy used for the purposes of expanding manufacturing and benefiting our local community.”
By Clodagh Rice, BBC News NI business correspondent
Workers gathered outside Wrightbus breathed a sigh of relief – there were even bottles of champagne opened in celebration.
The news came through on Friday morning that Jo Bamford has agreed in principle to buy the factory.
Work is ongoing on the details with the administrators – we don’t yet know how many of the workers will be kept.
The farmland that was a sticking point previously has been gifted by Jeff Wright to Mid and East Antrim Borough Council as a tribute to his father and generations of workers.
The council is in negotiations with Queens university – it hopes the site could be used an innovation project as part of the Belfast city deal.
Manufacturing NI tweeted that it was great news that a deal had been done which could lead to a deal being secured by the administrators, but added that Deloitte needed to be aware that “in saving some jobs at Wrightbus they don’t kill jobs in the SME supply chain who are owed millions”.
Wrightbus was started in 1946 from a tin shed in Ballymena by Robert Wright and his son, William – now Sir William Wright.
The Ballymena business was placed into administration and put up for sale last month.
The Wrightbus premises are owned separately from the manufacturing business and held in a company called Whirlwind Property Two, which is not part of the Wright group and is therefore not under the control of the administrator.
The property company is controlled by Jeff Wright, the former owner of Wrightbus.