Administrators are being appointed to the Port Glasgow yard and ownership is expected to transfer to the Scottish Government.
Finance secretary Derek Mackay visited the yard today where he set out the proposals which will safeguard the future of more than 300 workers at the site.
The firm took the first steps towards administration last week amid a stand-off with publicly-owned ferry firm Cal Mac over a deal to build two new ships. Costs on the original £97m contract have spiralled with neither side prepared to meet the additional bill.
Entrepreneur Jim McColl's Clyde Blowers bought Ferguson's out of administration five years ago and the government has already loaned Ferguson's £45m to stay afloat.
GMB Scotland Organiser Gary Cook said: "Nationalisation secures the immediate future of the yard and that is a very welcome development, particularly after all the recent uncertainty. "Our members were caught in the middle of a situation that had nothing to do with them and their relief will be palpable. It is five years since the yard went bust and the Scottish Government has prevented that from happening again. "We must be clear that nationalisation will not be a quick-fix and there will be challenges. There will for example be limits to the amount of private sector work for which the yard can compete but the alternative to nationalisation was closure and that was no choice at all.
"Our immediate priority is to secure the re-employment of the workers released last weekend because their skills are essential and then we will insist the government works with us to develop a proper industrial plan for the yard because lessons must be learned.
"We can now look to the future and everyone should do so with a sense of purpose. With vision and competency we can get on with building the ships Scotland needs and together we can grow jobs and prosperity on the lower Clyde."