There are now TWO LeBron James offspring who can dunk a basketball ... 'cause the Lakers star's youngest son, Bryce, just rattled the rim for the first time on Thursday night!!
Just a couple years after Bronny -- LBJ's oldest boy -- accomplished the feat ... Bryce did it in warmups for Sierra Canyon H.S., and LeBron was fired up to see it.
The King had courtside seats for the big moment ... and cameras captured a big smile on his face after Bryce threw it down.
"Ayyyyeeeeeee!