The 170-pound title fight is also part of the opening round of Bellator's Welterweight Grand Prix. MMAFighting.com first reported the matchup, which will take place at SAP Center.
MacDonald (20-5), of British Columbia, is coming off a failed bid to become a two-weight champion in Bellator. He challenged Gegard Mousasi for the 185-pound title in September but lost via TKO in the second round. It was MacDonald's first loss since signing with Bellator in 2017.
Despite the loss, MacDonald is still the welterweight champion. The belt will be on the line throughout the Welterweight Grand Prix, which officially began in September. Other participants include Douglas Lima, Neiman Gracie, Paul Daley and Michael Page.
Fitch (31-7-1) is riding a five-fight win streak, including a decision against Daley last May.