People born on or after July 1, 1997, and aged 18 or over will be eligible to independently apply for British National Overseas visas from the autumn.
The current scheme only permits those born after 1997 to come with their parents.
As many as 11,700 young Hong Kongers could take advantage of the new visa rules, the Home Office estimates.
The change is seen as beneficial as campaigners warn that more than nine in 10 people who have faced protest charges in Hong Kong have been too young to access the visa scheme that enables residents to travel to Britain.
During mass protests in Hong Kong in 2019, more than 10,000 people were arrested.
Data compiled by advocacy group Hong Kong Watch found that 93 per cent of more than 1,000 who had been tried by July 2021 were under the age of 25.
Tory MPs including Damian Green, Iain Duncan Smith and Tom Tugendhat backed the call to change the current visa scheme.
“I’m delighted that thanks to the scheme we introduced, thousands of Hong Kongers have already made the UK their home and integrated into communities across the country,” said Home Secretary Priti Patel.
"The further changes I have announced, which will come into effect this autumn, will continue to deliver on our historic and moral commitment to the people of Hong Kong."
The BNO visa scheme was launched by the UK in January 2021. It allowed an estimated five million holders of BNO status and their immediate families to apply for dedicated entry visas with a pathway to full citizenship.
So far, more than 120,000 have applied for visas with some estimates suggesting as many as 300,000 could eventually take advantage of the scheme. Of the 123,400 who have applied, 113,742 have been granted.
Under the new rules, young adults applying for visas will not need to submit their parent’s passport or ID document as part of the application process where they are unable to, but will have the option to do so.
Those eligible will be able to bring their partners and children under 18 years and adult relatives who have a high level of dependency.