The exercise, known as "Operation Kingfisher", was confirmed for the first time by cabinet minister in charge of no deal preparations Michael Gove.
Speaking to journalists in Belfast, he said the scheme "will be there so any businesses that may be temporarily affected by changes of circumstances that are related to Brexit can be supported".
It is thought fewer than 1,000 businesses are on the list, which includes several from the construction and manufacturing sector that are at risk because of their supply chains.
The plan was first conceived under the previous chancellor Philip Hammond as a way to inject cash into various sectors and regions after Brexit.
Government departments were asked to put forward candidates to the Treasury that may be at risk and could require help.
It's understood that overall control of "Operation Kingfisher" will still remain with the Treasury, but the scheme will be revamped.
It is expected to be discussed at the government's "exit strategy" committee when it meets next week.
Support would be given to businesses that are "fundamentally viable" but may have cash flow or other issues after Brexit.
Labour has accused the government of not being straight with the public over the risks of a no-deal Brexit.
Shadow chancellor John McDonnell said: "The lack of detail around Operation Kingfisher - we know nothing about how much money has been set aside, what businesses are eligible, or what kind of support will be available - shows just how half-baked this government's preparations are."
Under the previous chancellor, the "Operation Kingfisher" plans were separate from the funding put aside for Brexit preparations, and formed part of the £27bn of "fiscal headroom" built up to help with the impact of no deal.
A large amount, if not all, of that money has already been earmarked by new Prime Minister Boris Johnson for domestic spending commitments in areas like policing and education.
However shortly after taking office, new Chancellor Sajid Javid doubled the amount of money available to help prepare for no deal saying the Treasury was "ready to play a full role" in Brexit.
On Friday, the chancellor told Sky News he is not "frightened" at the prospect of a no-deal Brexit, insisting the British economy would eventually emerge even stronger.