"Not doing so is difficult because I love serving South Carolina more than anything," she said.
"I was moved to accept this new assignment for two reasons. The first is a sense of duty. When the President believes you have a major contribution to make to the welfare of our nation, and to our nation's standing in the world, that is a calling that is important to heed. The second is a satisfaction with all that we have achieved in our state in the last six years and the knowledge that we are on a very strong footing."
Haley, 44, the daughter of Indian immigrants who was born in Bamberg, S.C., has little foreign policy experience but has worked on domestic trade and labor issues. Her foreign policy work centers on negotiating with international companies seeking development deals in South Carolina and leading seven overseas trade missions during her two terms as governor.
Haley supported Sen. Marco Rubio, R-Fla., during the Republican primary and criticized Trump's campaign proposal to temporary ban Muslims from entering the United States.
In what was regarded to be a dig at Trump's campaign, she also criticized the "angriest voices" within U.S. politics and their "siren call" to voters during the Republican response given to President Barack Obama's State of the Union address earlier this year.
Despite previous criticism, Haley said she never disliked Trump after the president-elect visited her last week. In 2012, Trump made a $5,000 contribution to a pro-Haley political group.
"He was a friend and supporter before he ran for president, and was kind to me then. But when I see something I am uncomfortable with, I say it," Haley said. "When we met, it was friends who had known each other before."
Henry McMaster, South Carolina's lieutenant governor, would replace Haley as governor if she is confirmed.
"I will remain as governor until the U.S. Senate acts affirmatively on my nomination," she said Wednesday. "We still have much to do in South Carolina, and my commitment to the people of our state will always remain unbreakable, both while I continue to hold this office, and thereafter."