TAIPEI, Taiwan — Taiwan’s voters delivered a stinging rebuke of China’s rising authoritarianism on Saturday by re-electing President Tsai Ing-wen, who vowed to preserve the island’s sovereignty in the face of Beijing’s intensifying efforts to bring it under its control.

Ms. Tsai’s victory highlighted how successfully her campaign had tapped into an electorate that is increasingly wary of China’s intentions. It also found momentum from months of protests in Hong Kong against Beijing’s encroachment on the semiautonomous Chinese territory’s freedoms.

For China’s ruling Communist Party, the outcome is a dramatic display of the power of Hong Kong’s antigovernment protest movement to influence attitudes toward the mainland in other regions the party deems critical to its interests.

China’s authoritarian leader, Xi Jinping, has warned Taiwan that unification between the sides was inevitable. His party has sought to court Taiwanese with opportunities to work in the mainland while isolating Ms. Tsai’s administration and said that China would use force, if necessary, to prevent the island from taking steps toward formal independence.