The OK comes after a check under the National Security and Investment Act, letting ministers step in in deals involving sectors critical to national security.
The plant's old owner, Netherlands-based Nexperia Group, owned a 14 per cent share, making that 100 per cent in July 2021. However, the deal faced many questions due to national security worries from Nexperia's ownership by Chinese state-owned Wingtech Technology.
A check by the UK government in late 2022 said fears of possible influence from China messing up the country's semiconductor-making skills and knowledge-sharing worries. After this, Nexperia had to sell its share in the place.
US electronics biggie Vishay came in in November last year, saying it was buying the plant for a reported €163 million, which the government is an excellent way to save more than 400 jobs. After all, British industry never seems to go anywhere this day unless it is owned by some big US multinational.
The deal had to get a national security clearance, which Secretary of State Oliver Dowden has now given after a four-month wait.
"Following a detailed national security check, the deputy prime minister, in his role as secretary of state in the Cabinet Office, has let the planned buying of Nexperia Newport Ltd by Vishay Intertechnology Inc go ahead," the Cabinet Office said.
While NWF makes semiconductors, they are compound models, which are different from silicon-based computer chips. Its bits are, however, used in a range of things, from hoovers to cars.
The buy-out marks a new start for the plant, now called Newport Vishay. As the UK's biggest semiconductor maker, Newport Vishay wants to grow its work, especially in compound semiconductor R&D.
Although it said yes to the buying, the UK government has put strict rules on the deal.
Vishay has to tell the government of any future deals involving moving or getting to the factory by third parties, ensuring tight control over clever property and touchy information.
Vaughan Gething, Welsh minister for the economy, said he was happy for the plant's workers:
"Today's news brings safety to an excellent workforce after a long time of doubt, and I hope they can look forward to a new feeling of hope," Gething said.
Labour's shadow Welsh secretary, Jo Stevens, praised the decision as long-waited good news for Newport's workers but had a go at the government for delays in sorting out the matter.
Welsh secretary David TC Davies was pleased with the clearance and is looking forward to Vishay International's plans for the plant.