Lonzo Ball just won Christmas ... going full Big Baller style, copping a $350k Rolls-Royce for his dad, LaVar, and his mom, Tina, ... and their first ride was caught on video.

Ball unveiled the new ride on his social media, with the hashtag #ItsTheLeastICouldDo, although something tells us he knows he's doing the most.

Of course the Balls aren't strangers to fancy cars -- all the boys push Lamborghinis -- but we're guessing Lonzo felt it was time his dad got in on the act as well.