Master P's son, Mercy, balled out with 18 points in a huge playoff win over Sierra Canyon on Tuesday ... officially bringing Bronny James' high school basketball career to an end.
Sherman Oaks Notre Dame -- the #1 seed -- easily handled S.C. in the CIF Southern California Division 1 Regional, 80-61 ... punching its ticket to the state finals later this week.
STAR-STUDDED SHOWDOWN
There were some big names in the crowd as N.D. secured the win ... including Mercy's rap legend dad and French Montana.