"I would like to thank all of Cory's supporters at this extremely emotional time," wrote Ann. "Your support has been overwhelming ... thank you!"
Ann, who describes herself as a "Canadian mom, actor mom, designer/decorator,dancer," also referred to rumours about her son's ashes.
"The person releasing articles relating to my feelings and thoughts on how to take care of Cory's ashes has never been in contact with me.
"I have never met or spoken to this person He does not represent me or my wishes."
Ann does not use her Twitter account frequently but when she does it has often been to interract with Cory and his girlfriend Lea Michele's fans.
Ann replied to one Twitter user to say that she was "very proud" of her son and also promoted fansites dedicated to Cory and Lea.
Tributes have poured in for Glee actor Cory since he was found dead in a hotel room at the Fairmont Pacific Rim hotel in Vancouver on July 13.
Cory's family and Lea have both asked that their privacy was respected as they dealth with Cory's sudden death, which was caused by a toxic combination of heroin and alcohol.
Before Ann spoke out on Twitter, Cory's cousin Richard Monteith had represented his family by paying an emotional tribute to the star on Canadian news channel Global News.