Both tournaments have been moved from April to October.
In a statement, World Rugby said the health and safety of players, fans and everyone working on the event is their highest priority.
"This prudent decision has been taken in order to help protect the global rugby community and the wider public and was taken based on the World Health Organisation and relevant public authority travel and health guidelines. The decision is fully supported by stakeholders, including unions and commercial partners."
The Fiji men are five-time defending champions in the Hong Kong event, which they have won a record 19 times, while 2020 marks the first time Hong Kong will be an official event in the Women's Sevens Series.
The Hong Kong event also includes a men's and women's World Series qualifying tournament, with eight men's and eight women's teams competing for a permanent core-team spot on the 2020/21 circuit.
The Singapore Sevens will now take place on 10/11th October with the Hong Kong tournament to conclude the World Series on 16-18 October.