Boyce was 20 when he died in his sleep last month due to epilepsy. He played Cruella de Vil's teenage son, Carlos, in the "Descendants" franchise, which follows the children of Disney villains.
"Tonight's premiere of #Descendants3 is dedicated to #CameronBoyce and is a celebration of his talent and the joy he brought to the world. You'll always be in our hearts, Cameron ❤️," the channel wrote on Twitter.
The emotional, two-minute video that aired after the movie includes old interviews with Boyce, praise from cast members, outtakes and even footage of Michelle Obama's guest appearance on the show "Jessie," which Boyce also starred in.
"Everything you are ... Every smile, every laugh, every dance, every hug, every moment, everyone you touched ... you mean everything to us," reads the message interspersed throughout the video.
Disney Channel canceled the red carpet premiere for "Descendants 3" last month, saying that its parent company would instead donate to the Thirst Project, a nonprofit Boyce was heavily involved in that provides communities with safe drinking water.
Outside of his Disney roles, Boyce also appeared in "Eagle Eye" alongside Shia LaBeouf and "Grown Ups" with Adam Sandler.