Haley, 44, and the daughter of Indian immigrants, is the first woman and first person of color to be picked for the new administration.
Charismatic and popular in her home state, she was sharply critical of Trump during the campaign. She scolded what she called voices of hatred as being counterproductive. After initially supporting Sen. Marco Rubio of Florida, she backed Trump's rival Sen. Ted Cruz of Texas during the party's primaries.
But Haley later moved to mend relations with Trump and supported him in the general election.
In a statement released by his transition office, Trump praised Haley for having "a proven track record of bringing people together regardless of background or party affiliation to move critical policies forward for the betterment of her state and our country."
"She is also a proven dealmaker, and we look to be making plenty of deals," the statement said.
For the president-elect, who has picked several people for his administration so far who come from the right wing of the Republican party, the Haley pick represents a nod to more moderate forces, especially in the realm of global diplomacy.
Haley has virtually no experience in foreign affairs, however, and will have a steep learning curve. Most previous ambassadors to the U.N. have been steeped in diplomacy, and the post can be a complicated stew of negotiation, compromise and patience.
It is not clear how much influence the United Nations ambassador will have in the new administration. Trump was dismissive of the U.N. and other international venues during his campaign.
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