The 40-year-old Carter, who is the NBA's oldest active player, agreed to a one-year, $8 million deal, according to multiple media reports.
Last season with the Memphis Grizzlies, Carter averaged 8.0 points and 3.1 rebounds in 24.6 minutes per game.
The eight-time All-Star ranks 22nd on the league's all-time scoring list with 24,555 career points.
Hill agreed to a three-year, $57 million deal, according to reports. He averaged a career-best 16.9 points and 4.2 assists for the Utah Jazz last season. He played in just 49 games due to an assortment of injuries.
Hill declined a wealthier offer from the Jazz during the season and seemed intent on departing.
Randolph reached agreement on a two-year, $24 million deal and reunites with Dave Joerger, his former coach with the Grizzlies.
He was moved into a sixth man role last season by new Grizzlies coach David Fizdale and averaged 14.1 points and 8.2 rebounds. Randolph spent eight seasons in Memphis and made two All-Star teams.