The victory, the national US media said, elevated her to the national stage and almost a certain win later in the year.
If elected in the November elections, Haley would be the first Indian American female and also the first-ever female governor of South Carolina.
The 38-year-old overcame a series of allegations of extra-marital affairs, which she had denied, to win the nomination.
In the run-off to the primary elections on Tuesday, Halley defeated Congressman Gresham Barrett. The Indian-origin Republican candidate, a mother of two, was endorsed by top party leaders including Sarah Palin, the former Alaska Governor, and Mitt Romney, the former Massachusetts Governor.
US media reported that Haley, who was born as Nimrata Randhawa, starts as a favourite against Democrat Vincent Sheheen as South Carolina has strongly favoured the Republican.
The state has never voted for a Democratic presidential candidate since Jimmy Carter in 1976.
Haley, who was trailing behind most of her Republican rivals, started gaining ground and eventually won the Republican nominations soon after she was endorsed by Palin and Romney, both of whom campaigned in her favour.
Haley got 62 per cent of the total votes polled, while Barrett received 38 per cent. The Washington Post said the victory makes Haley not just the front-runner for the office this fall but a likely national GOP star.
'Even before Haley had officially become the nominee, the Republican Governors Association had all-but-endorsed her -- recognising that an Indian-American woman as their nominee was a terrific national storyline,' the daily said.
'Given Haley's background and the primacy of South Carolina in the 2012 Republican presidential primary process, she will almost certainly become a national figure in short order,' it added.
Echoing the same view, The New York Times remarked that the victory 'swiftly elevates her to become one of the leading faces of the national Republican Party' and puts her within one step of winning election in the fall as South Carolina's first female governor.
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