Dozier, who is ranked No. 21 in the ESPN 100, chose South Carolina over Louisville during a news conference at Spring Valley (S.C.) High School.
"South Carolina wouldn't be in the mix if I didn't feel like they had the players and coaches to [turn it around]," Dozier said. "I'm definitely excited to play along with them and get this going.
"It was just a feel. All the coaches did a great job recruiting, no one really better than the other. In the end, it just came down to how I felt."
His father and uncle played at South Carolina, and his sister is on the women's team.
Dozier can play multiple positions and will make an immediate impact for the Gamecocks in 2015-16. He becomes the centerpiece for Frank Martin's 2015 class, joining fellow ESPN 100 prospect Chris Silva.
Dozier took all five of his official visits, making trips to Michigan, North Carolina, Georgetown, South Carolina and Louisville during a six-week span in September and October.
Things seemed to be trending for the Cardinals coming out of the official visits, as Rick Pitino's program had made a strong push since five-star Antonio Blakeney decommitted in September. Martin's visit late last week, however, pushed the tide back in South Carolina's favor.
Dozier is the first domino in what is expected to be a fairly quiet early signing period. Top-25 prospects Skal Labissiere, Isaiah Briscoe and Derrick Jones will announce their college decisions Thursday on ESPNU, while four-star small forward Tevin Mack is expected to choose later this week. Nearly every other remaining top-100 prospect is likely to wait until the spring.