The 60-year old conservative, Park Geun-hye, will return to the presidential palace in Seoul where she served as her father’s first lady in the 1970s, after her mother was assassinated by a North Korean-backed gunman.
With more than 88% of the votes counted, Ms Park led with 51.6% to 48% for her left-wing challenger, human rights lawyer Moon Jae-in, giving her an unassailable lead that forced Mr Moon to concede.
Her jubilant supporters braved sub-zero temperatures to chant her name and wave South Korean flags outside her house yesterday.
She said she would work to heal a divided society, and told supporters at a rally in central Seoul: “This is a victory brought by the people’s hope for overcoming crisis and for economic recovery.
Ms Park will take office for a mandatory single, five-year term in February and will face an immediate challenge from a hostile North Korea.
She will have to deal with an economy in which annual growth rates have fallen to about 2%.
She is unmarried and has no children, saying that her life will be devoted to her country.
The legacy of her father, Park Chung-hee, who ruled for 18 years and transformed the country from the ruins of the 1950-53 Korean War into an industrial power-house, still divides Koreans.
For many conservatives, he is South Korea’s greatest president and the election of his daughter vindicates his rule. His opponents dub him a dictator who trampled on human rights and stifled dissent.
Ms Park has said she would negotiate with Kim Jong-un, the youthful leader of North Korea, but wants the South’s isolated and impoverished neighbour to give up its nuclear weapons programme.