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.