Cosby, 83, is currently serving a 3- to 10-year sentence in a prison outside of Philadelphia for drugging and sexually assaulting a former Temple University employee at his home in 2004.
The letter, which said the board’s decision was made on May 11, said Cosby was to “participate in and complete additional institutional programs.”
Council cited “Cosby’s failure to develop a parole plan” and a “negative recommendation from the Department of Corrections” as factors that contributed to the decision.
The letter said that at Cosby’s next meeting with the board, the board will review and consider whether he has successfully attended and completed a sex offender treatment and violence prevention program.
Andrew Wyatt, a spokesperson for the disgraced actor, said the news of the denial came as no surprise to Cosby, his family, friends and his legal team.
Last December, the Pennsylvania Supreme Court heard arguments over an appeal filed by Cosby’s legal team to overturn the conviction, and a decision on the appeal has yet to be rendered.
CNN’s Eric Levenson contributed to this report.