ARM shareholders have voted overwhelmingly to accept SoftBank's 24 billion takeover offer.
Around 95% of them voted overnight to back the acquisition by the Japanese firm, after ARM's board accepted the cash offer last month.
The 17 a share offer represents a premium of more than 40% on the chip designer's closing price and the deal is expected to complete on 5 September.
SoftBank's owner and chief executive Masayoshi Son gained support from the UK government by making legally binding pledges to double the firm's UK workforce over the next five years and keep its HQ in Cambridge.
But former City minister Lord Myners said the deal was an example of the UK "selling out of our winners".
He told BBC Radio 4's Today programme that if ARM was an American, German, or French company, or a Japanese company, it would not be able to be sold within 60 days.
"There would be a question of national significance and public policy to determine whether we should sell," he said.
He added that control of ARM would now pass to a "very heavily-indebted, very unfocused business in Japan which does not have a good record of buying foreign companies and continuing to invest in them".
Richard Holway, chairman of analyst group TechMarketView, said that since the 1980s all takeovers have "practically all been one way".
"Every quoted (and private) UK tech company is vulnerable. All the way from Imagination to Sage to MicroFocus to Aveva etc with everyone in between. The devaluation of the makes UK companies even more attractive. The US tax rules, making it difficult to repatriate overseas profits, also encourages US companies to acquire in the UK," he said.
He added that conversely, the UK's strength as a place to build and scale a tech company means that knowing you will get an exit is "no bad thing" for investors.
"Maybe that is our destiny - as an incubator of tech companies and serial entrepreneurs. There are probably worse fates," he concluded.
