News of Williams' deal was earlier reported by Yahoo! Sports.
Williams, a nine-year NBA veteran, averaged 9.1 points, 5.1 rebounds and 1.2 assists last season for the Utah Jazz.
He was the second Jazz forward the Hornets attempted to bring in this offseason, as Utah elected to match Charlotte's four-year, $63 million offer sheet to restricted free agent Gordon Hayward earlier Saturday.
The Hornets view Williams as a potential replacement for power forward Josh McRoberts, who previously agreed to a contract with Miami. Williams is also versatile enough to play small forward.
McRoberts' departure left the Hornets extremely thin at power forward and in need of some veteran help. Charlotte's only two power forwards on the roster were Cody Zeller, who is entering his second season, and Noah Vonleh, the ninth overall pick in this year's draft.
Coach Steve Clifford said Friday the loss of McRoberts was a "big hit" for Charlotte, calling him a valuable "connector" for the team.
"Not many guys of his size make the game easy for his teammates the way he does," Clifford said. "Not just offensively, but defensively, too. But I've said to his (now former) teammates that's what this league is about. We have other good players and we're still in the process of adding other players to our roster.
"What it will mean is, particularly on offensive part of the floor, we'll have to do things in a different way. No question he was a big part of what we did. Doesn't mean we have to take a step back, but we have to change."
Williams' addition should be popular among area Tar Heel fans.
Williams played college basketball at North Carolina, the same school as Hornets owner Michael Jordan, and helped the Tar Heels to a national championship as a freshman in 2005. He was the second overall pick in the 2005 NBA draft.
Information from the Associated Press was used in this report.