The 30-year-old actor – who plays Finn Hudson in the comedy musical – recently voluntarily admitted himself to a treatment facility for substance addiction and creator Ryan is impressed with Cory's brave decision.
He tweeted: "I am so proud of Cory Monteith and love and support him 100 percent.”
Cory's co-stars also added their support with Kevin McHale writing "Love you, Cory. So proud of you," and Jenna Ushkowitz tweeting: "Sending lots of love and light to Cory. We love you."
Chris Colfer tweeted, "Anyone who helps themselves is a hero in my book."
Meanwhile Dot Marie Jones called Cory “the sweetest man” and warned people not to judge others.
She wrote: "We are - and always will be - here for you. I love you always. Stay strong. You never know what someone is dealing with in their personal life. Don't pass judgement."
After Cory's admission to rehab was announced, his co-star and girlfriend Lea Michele issued a statement declaring her intention to stand by him.
She said: "I love and support Cory and will stand by him through this. I am grateful and proud he made this decision."
Lea later tweeted: “Thank you all so much for all your love, support, and encouragement. It's means the world to us..”