Zheng Yanxiong is known for dealing with a land dispute in southern China in 2011.
His new agency's remit will be to enforce a strict security law passed this week in Hong Kong.
Critics of the law say it erodes the territory's freedoms.
Crimes of secession, subversion and terrorism will be handed punishments of up to life in prison.
Separately, one of 10 people arrested under the new law during protests on Wednesday has become the first to be charged under it.
Hundreds were detained during the clashes.


US skips congressional review to approve arms sale to Israel
Partial resumption of air navigation in Qatar
Kuwait and Qatar thwart fresh wave of Iranian attacks
After a week of war, Trump demands Iran's 'unconditional surrender'
Ex-rapper's party set to sweep Nepal election
Israeli airforce pounds Beirut, Lebanon death toll rises
US releases Epstein-related FBI interviews mentioning Trump
Hezbollah warns Israeli residents to evacuate towns near border
