“A 24-year-old local man has been charged with one count of inciting others for secession and one count of terrorist activity,” police said in a statement.
A police source said the charges were brought against a man who drove his motorbike into a group of police officers on Wednesday during protests against the security law.
The source asked for anonymity in order to be able to speak freely.
Video footage captured by local television showed a man on an orange motorbike with a flag that declared “Liberate Hong Kong, Revolution of our Times” on the back.
He turned down a side street and drove into a group of riot police.
Bystander footage shot on a mobile phone captured a scene moments later, where the man was swiftly detained after he fell to the ground.
Police at the time said three officers were wounded.
Beijing’s new security law was enacted on Tuesday and kept secret until it became law, sending shockwaves through the city both for how it was imposed and the strangling of free speech provisions it contains.
It outlaws various acts viewed as subversion, secession, terrorism and colluding with foreign forces.
But legal experts warn it proscribes even peaceful political views.
Hong Kong’s government, for example, have announced that using the phrase “Liberate Hong Kong, Revolution of our times” is illegal under the secession and subversion provisions.
The terrorism offences are broad and include attacks on vehicles or transport networks and “using dangerous methods to seriously endanger public health or safety”.
The most serious security law offences carry punishments of life imprisonment.
Reporting by Associated Press