Hong Kong's High Court has ruled that a domestic helper from the Philippines should be allowed to apply for permanent residency in the city.
The case was brought by Evangeline Banao Vallejos, who has lived in Hong Kong since 1986.
The ruling follows a landmark judicial review and could lead to more than 100,000 other foreign maids winning rights to residency.
The government has said that it will appeal against the ruling.
The case has sparked widespread debate on equal treatment for foreign maids.
Mark Daly, the lawyer acting on behalf of Ms Vallejos, said that she was very pleased by the ruling.
"When we told her she said 'thank God'," he said, adding that it was a normal working day for her.
"It's a good win for the rule of law," he added.
Hong Kong's Secretary for Security, Ambrose Lee, said that the government would not process or approve right-of-abode applications for domestic workers while it appealed against the ruling.
"The government respects but is disappointed with the ruling," he said.
Some critics have said granting residency to domestic helpers would strain the provision of health care, education and public housing.
While other foreign nationals can obtain residency after working in Hong Kong for seven years, immigration rules exclude domestic helpers from seeking permanent residency.
Human rights lawyers and many domestic helpers argue that this is discriminatory.
Permanent residency means that a person can remain in Hong Kong indefinitely, vote and stand in elections.
But some politicians and commentators warned that allowing foreign domestic helpers to have permanent residency would allow them to bring their children and other relatives to the city, who would require education and housing.
Norman Carnay, programme officer at the Mission for Migrant Workers said that he welcomed the decision.
"We hope it will pave the way for Hong Kong to open its doors to equal treatment for migrant workers," he said.
But he added that right of abode was not necessarily a priority for many domestic helpers.
"From surveys of our community, the more pressing concerns are wages and working conditions," he said.
There are around 300,000 foreign domestic helpers in Hong Kong, mainly from Indonesia and the Philippines. It is thought that around 120,000 have lived here for more than seven years.
They are required to live with their employers and cannot accept other jobs.
Without the right to permanent residency, if a maid is dismissed by her employer, she must find another job as a domestic helper or leave Hong Kong within two weeks.
Hong Kong's domestic workers have a guaranteed minimum wage of 3,740 Hong Kong dollars ($480; £308) a month and day off each week, meaning their working conditions are better than other countries in Asia with large numbers of domestic helpers, such as Singapore.