She took the oath of office in the presence of Chinese President Xi Jinping, who arrived in the former British colony for celebrations marking 20 years since the territory’s handover to China.
Members of government and parliament were also sworn in. Lam and her cabinet are believed to be more loyal to Beijing than other contenders. She was backed by 777 of 1,194 electors at the March 26 vote.
Since the region’s return under Chinese rule, Hong Kong has been governed under a "one country, two systems" principle, which guarantees it wider autonomy and more freedoms than elsewhere in the country.