Speaking at a two-day work conference on Xinjiang that ended on Saturday, Xi said that China's Xinjiang strategy was correct "and must be adhered to in the long term."
"The whole party must treat the implementation of the Xinjiang strategy as a political task, and work hard to implement it completely and accurately to ensure that the Xinjiang work always maintains in the correct political direction," Xi added, according to state media.
"We must also continue the direction of Sinicizing Islam to achieve the healthy development of religion," Xi said. The Chinese leader added that "it is necessary to tell the story of Xinjiang in a multi-level, all-round, and three-dimensional manner, and confidently propagate the excellent social stability of Xinjiang."
Even before the mass detention policy, Muslims in Xinjiang faced growing restrictions on practicing their religion, from limits on wearing the veil or growing beards, to pressure not to fast during Ramadan.
Xi claimed current policies in Xinjiang have brought "unprecedented achievements" in economic growth, social development, and improvement in peoples' livelihoods. He added that "the sense of gain, happiness, and security among the people of all ethnic groups has continued to increase."
His remarks come amid rising condemnation from Western nations including the United States over alleged human rights abuses in the region. Last week, the US House of Representatives overwhelmingly approved a bill called the "Uyghur Forced Labor Prevention Act," which aims to prohibit certain imports from Xinjiang and impose sanctions on those responsible for human rights violations in the region.
Speaking at the United Nations General Assembly this month, French President Emmanuel Macron called for an official investigation into Xinjiang.
The Xinjiang government said in a statement to CNN that the birth rate in the region had dropped from 15.88 per 1,000 people in 2017 to 10.69 per 1,000 people in 2018. The statement said that the drop was due to "the comprehensive implementation of the family planning policy."
Former internees who spoke to CNN testified to receiving or being aware of forced sterilizations. Numerous other witnesses have spoken about widespread abuse and forced indoctrination in the camps.
CNN's Beijing bureau, Ivan Watson, Rebecca Wright and Ben Westcott contributed reporting.