"Friends would not have been the same without you," Aniston wrote, alongside a post that featured a scene from an episode of Friends, as well as a headshot of Tyler's character on the show, Gunther.
"Thank you for the laughter you brought to the show and to all of our lives," Aniston continued. "You will be so missed #JamesMichaelTyler 💔"
The scene she shared, came from the series finale, in which Tyler's Gunther -- the manager of the Central Perk coffee shop where the eponymous friends frequented -- finally confesses his long-held secret love for Aniston's Rachel in the culmination on a long-running gag throughout several seasons of the series.
According to the statement released by his rep, "Michael loved live music, cheering on his Clemson Tigers, and would often find himself in fun and unplanned adventures. If you met him once you made a friend for life."
Tyler was first diagnosed with prostate cancer in 2018, and went on the Today show this past June to open up about his diagnosis and to encourage others to get tested as early and regularly as possible.
"I'm sorry to say that I'm not with you today to announce that there's going to be a Friends movie. Actually, I'm here to let you know that in September 2018 I was diagnosed with advanced prostate cancer, which had spread to my bones," Tyler said during his appearance.
"I would have gone in earlier, [it] would have been hopefully caught earlier," he said, tearfully. He also urged viewers, "Next time you go in for a basic exam or just a checkup, please ask your doctor for a PSA checkup."
He is survived by his wife, Jennifer Carno, whom he wed in 2017.