Mr Wong was one of the top candidates emerging from unofficial primaries held by the pro-democracy camp as it aims to win a majority of seats in the 70-seat legislature in the September elections.
He told reporters: “We hope to let the world to know how we choose not to surrender, how we choose not to kowtow to China.”
Critics of the national security law Beijing imposed on the semi-autonomous territory on June 30 fear it may be used to thwart pro-democracy candidates.
The sweeping law bans secessionist, subversive and terrorist acts, as well as banning colluding with foreign forces to intervene in the city’s affairs.
The law also states that anyone convicted of endangering national security will be disqualified from running in city elections or holding public office.
The 23-year-old Mr Wong has been imprisoned twice for participating in 2014 pro-democracy protests. He also regularly speaks out against Beijing’s tightening control over the city and often meets with elected officials and politicians from the US and other countries.
He said: “With the threat of being extradited to China, with the uncertainty of being sent to a black jail in Beijing, with the possibility of facing a life sentence … I still hope to run for office and receive people’s mandate, and let the world know that we will continue our fight until our last breath.”
In 2017, four pro-democracy legislators including Nathan Law were unseated from the legislature after a court found that they had not taken their oaths and pledged allegiance to Beijing appropriately.
Two other pro-democracy representatives were disqualified in 2016 for invalidated oaths.
Mr Law fled Hong Kong for the UK after the security law was enacted and has said he will continue advocating for democracy in Hong Kong while abroad.
