Bronny James Jumps Over Bro In McDonald's Dunk Contest, But Loses To Duke Commit

Bronny James took flight at the McDonald's All-American dunk contest on Monday night ... leaping over his younger bro for a sick slam -- but in the end, it wasn't enough to beat out a Duke commit to win the event.

LeBron's offspring participated in the prestigious skills competition two decades after The King won it all back in 2003 ... and the 18-year-old came thiiiiiiis close to repeating Dad's feat.

Bronny, a 6-foot-3 shooting guard, opened the competition with a self-lob, reverse dunk that scored a 65/70. His second throwdown -- a self-lob, one-handed windmill -- earned him a 57/70 and a place in the finals.

The Sierra Canyon star opened up the championship round by bringing out his younger brother, Bryce -- and dunking all over him ... an impressive accomplishment, considering the 15-year-old is 6-foot-5.

The slam got him a 63/70 ... but when Bronny wasn't able to complete his second dunk in the finals -- Blue Devils signee Sean Stewart took home the event's crown.

Bron was largely impressed with his boy's performance -- the Lakers superstar live-tweeted the whole event, critiquing the judges' scores ... while praising some of Bronny's work. His wife, Savannah, meanwhile, attended it all in-person, and gave Bronny 10s for every dunk.

Despite the loss Monday night, Bronny will have another opportunity to show out in Houston this week ... the actual McDonald's All-American Game tips off at 6 p.m. PT on Tuesday.