The L.A. Lakers superstar and his longtime girlfriend, Denise Garcia, are expecting a Baby Baller together ... TMZ Sports has confirmed with multiple sources connected to the situation.

Zo and Denise have been dating since their days at Chino Hills H.S. ... and we're told Denise's family is excited to meet the baby and already loves it unconditionally.

We're told Denise is 4 months pregnant. We're told the baby is very healthy. No word on whether it's a boy or a girl ... but we're guessing LaVar is hoping for a hooper to continue the BBB legacy.

Congrats!!!