The 20-year-old died on Saturday (July 06) after suffering a seizure linked to an ongoing medical condition.
Stunned Sandler took to Instagram on Sunday to offer up a heartfelt tribute, calling Boyce, "the most decent kid around."
"Too young. Too sweet. Too funny. Just the nicest, most talented, and most decent kid around," Sandler wrote. "Loved that kid."
"Cared so much about his family. Cared so much about the world. Thank you, Cameron, for all you gave to us. So much more was on the way. All our hearts are broken. Thinking of your amazing family and sending our deepest condolences."
"Stranger Things" star Millie Bobby Brown also took to Instagram and posted a photo of Cameron with a heart above his image, and Kenny Ortega, the director of Boyce's hit Disney show "Descendants", wrote, "Cameron, You left a big piece of your heart for those of us who knew and loved you in this life and you left with a big piece of our hearts today. We will continue to carry your loving spirit forward. You are our forever boy."
"In your short time on this earth you lit it up with your incomparable talent and goodness," Kenny added. "I will be forever grateful to have known and worked with you."
"Thank you for sharing your amazing gifts with us all. God Bless you and may God watch over your Incredible and loving Family during this difficult time. Only Love..."
Boyce will be seen in the third "Descendants" movie, which is set for release next month (August 2019). He played Carlos De Vil, the son of 101 Dalmatians villain Cruella, in the Disney franchise.
Disney boss Bob Iger has also offered up a tribute to the tragic young star, writing, "The Walt Disney Company mourns the loss of #CameronBoyce, who was a friend to so many of us, and filled with so much talent, heart and life, and far too young to die. Our prayers go out to his family and his friends."
"Absolutely heartbreaking, my heart goes out to his friends and family," Zendaya tweeted, while Puth added he didn't know the young actor personally, but he looked "like he was someone who exuded wonderful, positive feelings and was a role model to many."
And Hozier recalled meeting Boyce for the first time, writing, "When we met I was taken aback by his energy and drive, his dedication to his craft and the sheer kindness he exuded. It was a joy to witness the man's skill."