The lawsuit is over an opinion piece Ms. Heard wrote for the Washington Post in which she called herself a victim of domestic violence. He denies any abuse.
Ms. Heard has sued back, with a $100m counterclaim against Mr. Depp. The closely watched civil trial, which is taking place in Virginia, is now in its second week.
Mr. Depp’s team has presented Ms. Heard’s claims of domestic violence as a “hoax” and a calculated strategy to ruin his reputation.
Speaking to the jury on Tuesday, Mr. Depp said the truth was all that mattered to him now.
“I never struck Ms. Heard in that way, nor have I struck any woman in my life,” he testified, adding that “her accusations sort of permeated the industry”.
“It’s been six years of trying times – so strange when one day you’re Cinderella, so to speak, and then in 0.6 seconds, you’re Quasimodo,” he said, describing how people’s attitudes towards him changed after Ms. Heard’s op-ed was published.
The trial has focused so far on Mr. Depp’s demeanor and whether he was ever verbally or physically abusive towards Ms. Heard. Lawyers for Mr. Depp have accused his ex-wife, an actress, of giving the “performance of her life” in her descriptions of the alleged abuse.