The often press-shy actor will appear in a pre-taped interview on CBS' "48 Hours Mystery" on Saturday.
"I firmly believe Damien Echols, Jason Baldwin and Jessie Misskelley are totally innocent," Depp said, according to a New York Post report. "It was a need for swift justice to placate the community. Damien Echols is on death row to be killed by lethal injection."
The "48 Hours" episode will discuss new DNA evidence and alleged juror misconduct that could potentially clear the West Memphis Three, according to the report.
After the gruesome beating deaths of three 8-year-old boys shocked the small Southern town, many activists believe authorities rushed to convict the West Memphis Three based more on the trio's dark clothing and love of heavy metal than facts.
The sensational trial, conviction and aftermath — which has divided the community and the world at large for more than 16 years — were documented in a pair of acclaimed films by directors Joe Berlinger and Bruce Sinofsky: "Paradise Lost: The Child Murders at Robin Hood Hills" and "Paradise Lost 2: Revelations." The pair went on to make "Metallica: Some Kind of Monster" after the band provided music to their West Memphis Three documentaries.
Depp and Metallica are joined in their support for the West Memphis Three by Eddie Vedder, Winona Ryder, Natalie Maines of the Dixie Chicks and Henry Rollins, who organized a benefit album for the trio a few years ago, to name a few.
Last month, Demi Lovato offered her support via Twitter, writing: "Can everyone just take a second to read this please www.wm3.org a truly worthy cause. Show your support!!" followed by, "FREE THE WEST MEMPHIS THREE!!! :(."
Echols, Baldwin and Misskelley were teenagers at the time of their convictions. The verdicts have continuously been challenged through legal channels, but they all remain in prison, with Echols on death row. Many believe that circumstantial evidence seemed to point to other potential suspects. Some members of the victims' families have publicly expressed their desire to see all of the facts in the case re-examined.