"It is with great pleasure that I am announcing our next U.S. senator to be Congressman Tim Scott," Haley said. "I am strongly convinced that the entire state understands that this is the right U.S. senator for our state and our country."
"He earned this seat for the person that he is," she said. "He earned this seat with the results he has shown."
Scott, who represents the 1st Congressional District, succeeds DeMint, who announced Dec. 6 he was resigning with four years left in his six-year term to lead the Heritage Foundation conservative think tank.
In his remarks, Scott stressed his fiscal conservatism and praised DeMint and the people who made him the person he is, notably his mother, The Washington Post reported.
"I am thankful for a strong mom that understood that love sometimes comes at the end of a switch," Scott said.
Scott, 47, is the first black U.S. senator from the South since Blanche Bruce of Mississippi in 1881, The (Columbia, S.C.) State reported.
DeMint, of Greenville, reportedly favored Scott as his successor, and Haley has said she wanted to appoint someone with the senator's ideals, The State said.
Scott serves until a special election in 2014 for the final two years of DeMint's term. He is expected to run in the special election.
Haley said last week she planned to appoint a successor she thought could keep the seat in Republican hands.