The 'Conan O'Brien Show' host was told the sad news that the 'Mrs. Doubtfire' actor - who was found dead aged 63 in an apparent suicide yesterday - had passed away while filming his Monday night show and after coming back from a commercial break he delivered the shocking news to his studio audience.
A clearly emotional Conan looked into the camera and said: ''This is unusual and upsetting but we got some news during the show that Robin Williams has passed away. We tape these shows a few hours early and by the time you see this now on TV I'm sure that you'll know.
''I'm sorry to anyone in our audience that I'm breaking this news. This is absolutely shocking and horrifying and so upsetting on every level.''
Later on in the show, one of Conan's guests, 'The Lego Movie' star Will Arnett, paid tribute to the Hollywood legend, who he starred alongside in 2006 comedy film 'RV'.
He said: ''As funny as he was, he's truly one of the all time greats, he was even better as a person, he was just fantastic. He was one of the loveliest and sweetest and kindest guys I've ever worked with.''
Several stars have also paid tribute to the actor - who leaves behind wife Susan Schneider and three kids, 31-year-old Zachary, 25-year-old Zelda and 22-year-old Cody - including Hugh Jackman, who described him as a ''genius''.
He tweeted: ''Robin Williams ... true gentleman... acting great... comedic legend... genius. (sic)''
What's more, several fans have also paid tribute to the late actor at the iconic bench used in 1997 drama movie 'Good Will Hunting', one of his biggest films, at Boston Public Gardens in Boston.
Some have left flowers at the scene, while others have scrawled some of his famous quotes from his various movie roles on the nearby pavement.