Ex-MLB Star Mo Vaughn Admits To Using HGH

Ex-MLB star Mo Vaughn is fessing up to using human growth hormone during his career ... claiming he was trying to do whatever it took to recover from a knee injury.

57-year-old Vaughn -- who was named in the Mitchell Report in 2007 -- made the admission for the first time in an interview with The Athletic ... saying he "was shooting HGH in my knee" in the latter part of his time in MLB in hopes of staying on the field.

"I was trying to do everything I could," Vaughn said. "I knew I had a bad, degenerative knee."

"Whatever I could do to help the process..."

Vaughn suffered the ailment in the 1999 season opener while chasing a fly ball ... and even though he went on to play 139 games that year, he eventually had to walk away from the game due to his medical issues.

Vaughn distanced himself from baseball after his retirement ... but according to the outlet, it was due to his anger over failing to achieve more on the diamond -- not his ties to the Mitchell Report.

The investigation stated Vaughn bought HGH three separate times in 2001 -- four years before it was banned from MLB -- and got it from a former Mets batboy.

Vaughn -- a former MVP and three-time All-Star -- played the majority of his career with the Boston Red Sox before stints with the Anaheim Angels and New York Mets.