His jersey's got the Swoosh ... but Lonzo Ball says he's still a BBB guy at heart -- and the proof is on his feet. 

The L.A. Lakers rookie was at an NBA rookie photo shoot with teammate, Kyle Kuzma, when they started showing off their new Lakers uniforms, made by Nike. 

That's when Lonzo told the camera, "I know you see the Nike jersey on ... it's still Triple B's though!" 

He then pointed down to his $495 Big Baller Brand shoes. 

Daddy likey.