LeBron James' 14-Year-Old Son, Bryce, Dunks For 1st Time, Dad's Proud!

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!!!!!," said LeBron, who actually captured the dunk with his own cell phone camera. "Yo WTH man."

The dunk was pretty sweet -- Bryce took off on two feet and slammed the ball home with one hand. And, considering Bryce is just a 14-year-old freshman, it's likely the first of many.

Of course, Bronny is already killin' it a couple years after his first dunk -- he's considered one of the best recruits in the class of 2023 ... dunking the ball with ease and hearing from all of the top colleges.