Mr Boyce’s death was confirmed by his family on Saturday night to ABC News.
The TV and film star died in his sleep as the result of “an ongoing medical condition”, a spokesman for the family said.
“It is with a profoundly heavy heart that we report that this morning we lost Cameron,” the spokesperson told the American broadcaster.
“He passed away in his sleep due to a seizure which was a result of an ongoing medical condition for which he was being treated.
“The world is now undoubtedly without one of its brightest lights, but his spirit will live on through the kindness and compassion of all who knew and loved him.
“We are utterly heartbroken and ask for privacy during this immensely difficult time as we grieve the loss of our precious son and brother.”
Mr Boyce, from Los Angeles, made his acting debut in the horror film Mirrors at just 9 years old.
This really shows how scary life is, how quickly it can all end just like that. Tell the people in your life you love them whenever you can, you never know if it’s the last time you’ll get the chance💔RIP Cameron Boyce, you were loved far more than you could’ve imagined🙏🏼♥️ pic.twitter.com/oSOb2WEJ7t
— Dizzy✨ (@dizzygold_) July 7, 2019
Two years later, he appeared in the blockbuster Adam Sandler movie Grown Ups, as one of Sandler’s children.
His role in the musical fantasy films Descendants, which led US cable TV film ratings in 2015 and 2017, catapulted him to stardom.
Responding to the news of his death, a Disney Channel spokesperson said: “From a young age, Cameron Boyce dreamed of sharing his extraordinary artistic talents with the world.
“As a young man, he was fuelled by a strong desire to make a difference in peoples’ lives through his humanitarian work.
“He was an incredibly talented performer, a remarkably caring and thoughtful person and, above all else, he was a loving and dedicated son, brother, grandson and friend.
“We offer our deepest condolences to his family, cast mates and colleagues and join his many millions of fans in grieving his untimely passing. He will be dearly missed.”
The young actor had dedicated himself to charity work in recent years, introducing former Vice President Joe Biden at his Biden Courage Awards in March.
Last year, he was honoured with a Pioneering Spirit award for his work with the Thirst Project, a nonprofit for which he raised around £24,000 ($30,000) to build wells for clean drinking water in Swaziland.
The 20-year-old, who had 8.1 million followers on Instagram, posted a head shot of himself on Friday.
Devastated fans have used the image as a platform to share their grief over Mr Boyce’s death.
One mourner commented on the Instagram picture: “Met you twice and both times you were such a honest modest person with the most ambition to help others with your platform. And you did.
“One of the very few honest people in show business everyone. And he left a legacy behind.
“One love to your family. God has other plans for you. Rest in peace.”
The Disney star was due to appear as a series regular in HBO’s new show Mrs. Fletcher and a TV spinoff of the film American Satan.
The YouTube sensation Brian Awadis, known by his online name FaZe Rug, tweeted a tribute to the young star on Sunday.
He wrote: “I don’t even know what to say. Rest In peace Cameron Boyce. He was a big part of my childhood and gone way too fast. This one hits different.”