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 and Iran signal a peace deal is close
Qatar rejects media report on energy production decisions
Trump says Iran war deal close as Strait of Hormuz tensions linger
Victims' families mark Air India crash anniversary with prayers and tributes
Ebola outbreak spreads to crowded displacement camp in Congo
Fire breaks out at New Zealand's Wellington airport, disrupting flights
Ukraine and Russia trade overnight drone strikes, officials say
UN says Taliban arrest 30 women for violating hijab rules in Afghanistan
