Yes, you can hire foreigners who have a valid work visa.
The Hong Kong government advises employers to give first preference to the local workforce for filling job vacancies, but foreigners who possess special skills, knowledge or experience are allowed to enter and stay in Hong Kong for employment as professionals.
As an employer, you should assist your employee apply for a working visa, before they could begin working in Hong Kong. More details on the application process can be found on the Immigration Department’s website. It is a criminal offence for a foreigner to work in Hong Kong without a valid work visa.