Justin Bieber: This Is How We Roll, Little Bro

Justin Bieber gave his baby brother a taste of baller's paradise ... docking his yacht for lunch.

The Biebs and his 6-year-old bro, Jaxon, hit up Seaspice in Miami Tuesday for some grub ... pear and Gorgonzola ravioli, short ribs and mojitos ... Jaxon's was virgin.

The tab topped $300 ... and the Biebs made the waiter's day with a $200 tip.

See ... Justin is a role model.