A shirtless James, wearing grey shorts, made a one-handed throw from the baseline in front of Cleveland's bench. The ball sailed through the basket at the opposite end.
Video of the shot was taken by James' longtime personal trainer, Mike Mancias. It surfaced on Twitter shortly after the end of Cleveland's practice before Sunday's scheduled Game 4 against the Celtics.
Cleveland leads the series, 3-0.
A little later, Houston centre Dwight Howard, wearing a yellow back pack, hit a shot from nearly the same spot, throwing one in with an underhand motion at his team's practice in Dallas.
His shot also surfaced on Twitter.