Stamos first worked with Saget nearly 35 years ago when Full House premiered in 1987, and co-starred on the show for eight seasons. The pair worked together again when the show got revived on Netflix with Fuller House and they remained close throughout the years.
Back in August, Saget celebrated Stamos' 58th birthday with a heartfelt post, calling the actor his brother.
"Today is a special day. Today is the day that my brother John Stamos was born. To say we are like brothers is an understatement. We have been through so much together for 35 years. High, lows- The usual you go through with your closest of people in your life. But what I have to say here, is how damned lucky I am to have John in my life. He has always been there for me. Even when I could be unbearable. Anyone who knows him knows what a beautiful person he is. And I’m not talkin’ about his gift of looks. I’m talking’ about the gift of his heart. I’ve learned so much from John, and I am truly blessed to have this good man as my brother. He deserves the happiest birthday of birthdays."
The Orange County Sheriff's Office confirmed the news on Twitter Sunday afternoon, writing, "Earlier today, deputies were called to the Ritz-Carlton Orlando, Grande Lakes for a call about an unresponsive man in a hotel room. The man was identified as Robert Saget & pronounced deceased on scene. Detectives found no signs of foul play or drug use in this case. #BobSaget"
The Medical Examiner’s Office will ultimately determine cause and manner of death, the Orange County Sheriff's Office added in a statement to ET.
Saget has been on his I Don't Do Negative stand-up tour of the country, and performed on Saturday at the Ponte Vedra Concert Hall in Jacksonville, Florida.