Moss took the stand in March via video link to deliver a few minutes of testimony, during which she denied Heard’s claim that Depp had pushed her down the stairs in the Nineties.
The model – who dated Depp between 1994 and 1998 – said that she did fall down a set of stairs when she and Depp were on holiday in Jamaica, and that he had helped her up at the time.
During a recent appearance on BBC Radio 4’s Desert Island Discs, Moss told presenter Lauren Laverne: “I know the truth about Johnny. I know he never kicked me down the stairs. I had to say that truth.”
Last month, a jury found that Heard had defamed Depp on all three counts and awarded him $10m (£8m) in compensatory damages and $5m (£4m) in punitive damages.
Heard was awarded $2m (£1.6m) in compensatory damages, but no punitive damages.
At the time of her testimony, Moss recalled: “We were leaving the room, Johnny left before I did, and there had been a rain storm. As I left the room, I slid down the stairs and I hurt my back.
“I screamed, because I didn’t know what had happened to me and I was in pain. He came running back to help me and carried me back to my room, and got me medical attention.”
Moss added that Depp “never pushed me, kicked me, or threw me down any stairs”.
The defence declined to cross-examine Moss.
Viewers watching the trial spotted that Depp appeared to be smiling at the screen on which he was watching Moss’s testimony.