The school announced the honour Saturday night during the Bruins' football game against Southern California.
Robinson played baseball, basketball and football and ran track at UCLA from 1939-41 before breaking baseball's colour barrier with the Brooklyn Dodgers. The No. 42 was painted on the Rose Bowl turf.
Although Robinson wore No. 28 as a UCLA football player, the school chose his historic Dodgers number for the program-wide honour.
UCLA is honouring the 75th anniversary of Robinson's arrival on campus. On Friday, the school collectively named 22 sports facilities the Jackie Robinson Athletics and Recreation Complex.
Three UCLA athletes who currently wear No. 42 will continue to wear it until they graduate.