Downey, 50, was among 91 others who were pardoned today by Gov. Brown in his annual Christmas Eve proclamation.
The pardon reads, "Robert John Downey Jr. ... has lived an honest and upright life, exhibited good moral character and conducted himself as a law-abiding citizen."
"By the laws of the this state ... Downey Jr. has paid his debt to society and earned a full and unconditional pardon," it concluded.
Long before he made a comeback as the star of "Iron Man," Downey was arrested on a Los Angeles County highway and later convicted of felony drug possession after authorities found cocaine and heroin along with a gun in his car. In 1999, he was imprisoned for violating his parole.
Though this doesn't mean Downey's criminal record is now scrubbed clean, the Oscar-nominated actor can now have other privileges, such as the right to vote.