Streaming service DAZN also posted on X (formerly Twitter) that the fight was a "done deal."
Multiple US media outlets had reported Thursday that the fight was in the works, with negotiations apparently complicated by the fact that Alvarez and promoter Premier Boxing Champions had parted ways last week.
Alvarez, who owns a record of 60-2-2 with 39 knockouts, claimed the undisputed super middleweight title when he defeated Caleb Plant in November 2021, unifying the WBC, WBA, WBO and IBF titles.
In September, he earned a devastating unanimous-decision victory over Jermell Charlo to retain his belts, knocking down the previously unbeaten Charlo in the seventh round as he became the first to defend all four titles for a third straight time.
In the bout set to coincide with the Cinco de Mayo holiday that's especially popular with Mexican-Americans, Alvarez will face another unbeaten in compatriot Munguia, who brings a record of 43-0 with 34 knockouts to the bout.
Munguia will be Alvarez's first Mexican opponent since he beat Julio Cesar Chavez Jr. in 2017.