In his speech to the twice-a-decade Communist Party congress, Xi made it clear that there will be no loosening of the party's control over the country's affairs during this "new era", in which he envisions China becoming a superpower by 2050.
He warned that social tensions and problems should be met with the strengthening of "governance based in law," and made multiple stern warnings to those supporting independence for semi-autonomous Hong Kong, and for self-governing Taiwan, which Beijing considers a renegade province.
"We will never allow anyone, any organisation, or any political party, at any time or in any form, to separate any part of Chinese territory from China," Xi said.
In recent years and months, the government has enacted several laws on internet control and other measures in the name of national security, giving a legal basis for its tightening grip on society.
It has also jailed several mainland citizens who spoke out in support of Hong Kong's democracy movement and arrested a Taiwanese NGO worker, Lee Ming-cheh, putting him on trial last month for "subverting state power."
"Emboldened by the national security laws passed by Xi, police will likely go after anyone who dares to criticise government policies," Frances Eve, researcher for the overseas Chinese Human Rights Defenders group, told AFP.
"There will be more crackdowns, arrests, mass surveillance and censorship."
While Xi has also presided over efforts to improve the professionalism of the judiciary, such as raising criteria for the appointment of judges, the reforms have not led to better treatment of government critics.
More than 200 Chinese human rights lawyers and activists were detained or questioned in a police sweep in 2015 that rights groups called "unprecedented."
In July, the authorities ignored international pleas for mercy as they refused to free democracy activist and Nobel Peace Prize laureate Liu Xiaobo before as he died of liver cancer.
Liu's death in custody triggered rage and frustration among the Chinese dissident community, and engendered a sense of hopelessness under Xi.
Margaret Lewis, an expert in Chinese law at Seton Hall University, said freedoms protected under international treaties "are under constant attack in China today".
"Police are by far the strongest component of the 'iron triangle' of police, prosecutors, and judges in the criminal system," Lewis told AFP.
Amnesty International researcher Patrick Poon said Xi's speech last week signalled that China will continue to use its laws to "crack down on dissidents in the name of protecting national security".
In recent years, rights groups noted an uptick in police harassment of China's most vocal critics, especially around major events, with activists getting sent on government-sponsored "holidays" away from Beijing.