James departed the Lakers' 99-94 loss to the Hawks in the first half after forward Solomon Hill made contact with his lower right leg while going for a steal. Hill was called for a foul on the play, which occurred near the start of the second quarter.
The 36-year-old James immediately shouted in pain and fell to the floor, clutching his right leg. The Lakers used a timeout to check on the 18-year NBA veteran, with multiple teammates and coaches surrounding James while he was down on the court.
"I haven't necessarily seen him scream and scowl like that probably ever," Lakers forward Kyle Kuzma said.
James knocked over a chair in frustration as he walked to the locker room. He underwent X-rays and an MRI on his right ankle following the game, which revealed the high ankle sprain.
"Nothing angers and saddens me more than not being available to and for my teammates! I'm hurt inside and out right now," James wrote on Twitter. "The road back from recovery begins now. Back soon like I never left."
After the game, Hill penned a message to critics who thought he tried to intentionally injure James.
"Would never disrespect the game and take a player out purposely," Hill wrote. "[James] knows that. That's all that matters to me. Praying for a speedy recovery."
Entering Saturday's game, James was averaging 25.8 points, 8.1 rebounds and eight assists this season.