Lebron James — Marries High School Sweetheart … Beyonce Sings at After Party

Lebron James tied the knot in California last night — and instead of some crappy band “We Are Family” — playing at the reception … they got JAY-Z and BEYONCE!!!!

The Miami Heat forward and his fiance Savannah Brinson made things official during a ceremony in San Diego at the Grand Del Mar Hotel … after dating 12 years.

According to reports — the 28-year old basketball player was joined by teammate Dwayne Wade and his girlfriend Gabrielle Union … as well as Jay-Z and Beyonce who performed “Crazy in Love” at the reception.

… and you thought the picture booth at your wedding was cool.