About 300,000 people are expected to leave Hong Kong for Britain using a new visa route which opens on Sunday.
Hong Kong's British National (Overseas) passport holders and their immediate dependants will be able to apply for the visa using a smartphone app.
UK Prime Minister Boris Johnson said the move honoured the UK's "profound ties of history and friendship" with the ex-British colony.
The visa was announced in July after China imposed a new security law in Hong Kong.
Beijing has previously warned the UK not to meddle in domestic issues.
Those who apply and secure the visa will be able to apply for settlement after five years and then British citizenship after a further 12 months.
Although there are 2.9 million citizens eligible to move to the UK, with a further estimated 2.3 million dependants, the government expects about 300,000 people to take up the offer.
The prime minister said: "I am immensely proud that we have brought in this new route for Hong Kong BNOs to live, work and make their home in our country.
"In doing so we have honoured our profound ties of history and friendship with the people of Hong Kong, and we have stood up for freedom and autonomy - values both the UK and Hong Kong hold dear."
The visa fee to stay for five years will be £250 ($NZ478) per person - or £180 for a 30-month stay - and there is an immigration health surcharge of up to £624-a-year.
From 23 February BNO status holders who hold an eligible biometric passport will be able to use an app to complete their application from home.
Home Secretary Priti Patel said this was to give applicants greater security amid fears they could be identified and targeted by the authorities.
"Safeguarding individuals' freedoms, liberty and security is absolutely vital for those individuals that go through this process," she said.
The BNO status was created before the UK handed responsibility for Hong Kong back to China in 1997.
Before Hong Kong was returned, the UK and China made an agreement to introduce "one country, two systems", which meant, among other things, rights such as freedom of assembly, free speech and freedom of the press would be protected.
The agreement signed in 1984 was set to last until 2047.
But the UK has said this agreement - known as the Joint Declaration - is under threat because the territory passed a new law in June that gives China sweeping new controls over the people of Hong Kong.
China has said the law is necessary to prevent the type of protests seen in Hong Kong during much of 2019. However, the law has caused alarm both in Hong Kong and abroad, with opponents saying it erodes the territory's freedoms as a semi-autonomous region of China.
- BBC