Playing against Titus Ashby, the young YouTube sensation, Bryant hit just four shots on a 6-foot-6 hoop from 18 feet.
"I was fouled," said Bryant after struggling to convert.
[Updated at 12:09 p.m.: Bryant can't blame his performance on his Achilles injury. He posted a picture with Titus on Twitter back in March, suggesting the competition was taped well before the Lakers All-Star was hurt.]
Titus also hit four on a 3-inch hoop from 6 feet, tying the five-time NBA champion.
"Do you think you can beat Kobe?" asked Kimmel.
"Yeah," said Titus, whose shot at the buzzer for the win didn't fall.
Titus' video on YouTube has received nearly 12 million hits since early February.
Bryant was injured April 12 in a win over the Golden State Warriors. He had surgery April 13, with his return to the game projected for six to nine months -- which could be as early as opening night in October.