Scottish Secretary Ian Murray said skilled Scottish jobs in communities in the Western Isles and Fife had been secured.
He added: “Navantia’s investment will not only secure the future of all four UK yards, but also encourage future support for UK shipbuilding and fabrication – a vital cornerstone of our defence and clean energy sectors.”
Matt Roberts, national officer with the GMB union, said the buy-out was a positive step to retaining manufacturing in the UK.
“Without a steady drum beat of work these yards will continue to struggle. GMB will continue the fight to ensure that does not happen,” he said.
Unite general secretary Sharon Graham said the union had been working “day and night” to secure the interests of the workers at Harland & Wolff.
She said: “After countless meetings with government, the employer, and prospective buyers, we now have a good news story offering real hope for the future. Unite will always do whatever it takes to fight for workers’ interests.”