The 31-year-old Mancini finalized a $14 million, two-year contract with Chicago in January. He batted .234 with four homers and 28 RBIs in 79 games with the Cubs.
A six-year veteran, Mancini became an inspirational figure in baseball after being diagnosed with colon cancer in 2020. He returned to the diamond in 2021 and then helped the Orioles contend for a playoff berth in 2022 before being traded.
Mancini has 129 home runs and a .775 OPS in 831 career games.
Candelario is in the starting lineup Tuesday, playing first base and batting sixth in Tuesday night's game against the Cincinnati Reds.
The Cubs got Candelario and cash from the Washington Nationals for minor league left-hander DJ Herz and infielder Kevin Made on Monday.
Candelario, one of the top hitters on the market ahead of Tuesday's trade deadline, hit .258 with 16 homers and 53 RBIs in 99 games with Washington. He signed a $5 million, one-year contract with the Nationals after he was non-tendered by Detroit in November.
Candelario, 29, signed with Chicago in 2010 and made his big league debut with the Cubs in 2016. He was traded to Detroit with fellow infielder Isaac Paredes for catcher Alex Avila and reliever Justin Wilson at the 2017 deadline.
The Associated Press contributed to this report.