Williams, a 5-foot-10, 176-pound running back from New London (N.C.) North Stanly, selected UNC over scholarship offers from Clemson, Georgia, NC State, and South Carolina, as well as nationwide interest.
"[UNC] just feels at home up there," Williams said. "The coaches are great. It's not too far from home, so if anything happens at my house, I can come home pretty quickly."
Specifically with the coaches, UNC assistant coach Chris Kapilovic was one of the first coaches to express interest in Williams. Kapilovic followed that up with establishing a great relationship with Williams.
"He just let me know how much they like me," Williams said. "I feel like [UNC] is the best school for me and he allowed me to realize that."
After coming to the decision at church on Sunday, Williams wanted to talk it over with his head coach, Ralph Jackson, on Monday morning before actually pulling the trigger.
"He supported me but told me I needed to be 100-percent about it," Williams said. "I knew that I was 110-percent."
With Jackson's blessings, Williams went ahead and made the call to Kapilovic and Larry Fedora.
"They just were really happy," Williams said. "They did seem shocked, because of how early it was. But that's how I wanted it to be – I didn't want to tell anybody. But they were very excited."
Williams wanted to keep it to himself primarily because he had a lot of pro-UNC influences in his community, including on North Stanly's coaching staff where former Tar Heel Quan Sturdivant is an assistant coach.
"I really tried to zone them out and make the decision on my own," Williams said. "It probably did [help] just a little bit, but I tried not to let it affect it at all."
Originally, Williams wanted to wait at least until closer to his junior season to make a decision.
"I didn't want to do it this early, but I feel like it's the right time," Williams said. "Everything happens for a reason. I know for a fact I'm going to be there. I know it's early, but I know it's right."
Despite the earliness of the pledge, Williams says he's finished with the recruiting process and won't visit any other schools.
"I'm not going to visit anywhere else," Williams said. "I'm a Tar Heel."
Williams plans to return to Chapel Hill for UNC's next home game against East Carolina and also attend the first half of "Zero Dark Thursday" against Miami.
Williams's focus now is his sophomore season. North Stanly is 2-1 and Williams has rushed for 437 yards and two touchdowns.
"Antonio is a difference maker to start with," North Stanly head coach Ralph Jackson said. "He's a kid that has committed himself to the weight room and the program. He's a kid that any coach in America would want to coach.
Williams immediately became North Stanly's starting running back as a freshman. He broke T.A. McClendon's Stanly County freshman record for rushing yards (1,412 yards) on 261 carries. He scored a total of 16 touchdowns (13 rushing) and caught 14 passes for 237 yards. Following the season, he was named a MaxPreps Freshmen All-American.
"He's more of a power running back," Jackson said. "He's not the fastest, but I'm telling you right now once he gets down hill his first few steps are very explosive."