New Delhi, Dec. 15 -- Chile's ultra-conservative former lawmaker Jose Antonio Kast secured a stunning victory in the presidential election Sunday, defeating the candidate of the center-left governing coalition and setting the stage for the country's most right-wing government in 35 years of democracy.

Kast won 58.2% of the votes as Chileans overwhelmingly embraced his pledge to crack down on increased crime, deport hundreds of thousands of immigrants without legal status and revive the sluggish economy of one of Latin America's most stable and prosperous nations. Kast's supporters erupted into cheers in the street as results trickled in, shouting his name and honking horns.

His challenger, communist candidate Jeannette Jara, clinched 41...