Hong Kong will now be treated the same as mainland China,” the president told reporters at the White House.
Mr Trump said he had also signed bipartisan legislation to impose sanctions on Chinese officials who crack down on rights in Hong Kong.
The US has been paring back Hong Kong’s special status over the last few weeks.
“No special privileges, no special economic treatment and no export of sensitive technology,” Mr Trump said in Tuesday’s announcement from the White House.
The territory, a former British colony, enjoys unique freedoms not seen in mainland China.