Posting on Monday (October 23), the Friends legend wrote alongside a photo of himself in the frothy water: "Oh, so warm water swirling around makes you feel good? I'm Mattman."
Aged just 54, Perry - beloved by millions of TV fans for his role as the wisecracking Chandler Bing - was pronounced dead at his Los Angeles home yesterday (October 28) following what local police described as a water rescue.
According to TMZ, an investigation is ongoing, with foul play already being ruled out.
A friend of the actor's told The Daily Mail in a statement: "Everyone is in a total state of shock. People are crying on the phone and struggling to accept this news.
"It's no secret that he struggled with drugs and alcohol for years but the last time I spoke to him, which was within the last few weeks, he seemed to be in a good place. He was upbeat and sounded sober and positive.
"He'd been to rehab 17 times and nearly died from opioid abuse but he was someone who was sincere about taking his life, and his sobriety, one day at a time. It's such tragic news. Everyone is praying he didn't relapse. Matt was a genuinely lovely guy.
"He was always the first to welcome newcomers to the group and would always volunteer to help and be of service. We are all struggling to come to terms with this terrible news."
Perry is survived by his father John Bennett Perry, mother Suzanne, stepfather Keith Morrison, stepmother Debbie Boyle, and five half-siblings.
Watch: Friends star Matthew Perry dies aged 54