King Beast and Queen Belle marry and unite all the kingdoms into the United States of Auradon, where they are elected the leaders of the new idyllic kingdom. All of the villains, sidekicks, and accomplices are forced after their defeat to live imprisoned on the Isle of the Lost, a forbidden island surrounded by a magical barrier that inhibits magic and escape.
In present-day Auradon, Prince Ben, the teenage son of King Beast and Queen Belle, is about to ascend the throne. His first official proclamation offers a chance for four selected trouble-making teenage children of villains from the Isle of the Lost to live among them in Auradon and attend Auradon Prep. He chose: Carlos, son of Cruella De Vil; Jay, son of Jafar; Evie, daughter of The Evil Queen; and Mal, daughter of Maleficent. Adam is at first unwilling to go with it, because their parents committed unspeakable crimes. These villainous descendants are given news of this by Maleficent, that they are invited into Auradon to attend a prep school alongside the teenage children of iconic heroes. However, the evil teens are under pressure by their parents to help all the villains regain power by stealing the Fairy Godmother's Magic Wand. Mal, Evie, Jay and Carlos arrive at Auradon Prep and set out to steal the wand using Evie's magic mirror to locate the wand at a nearby museum. There, after seeing statues of Maleficent, Jafar, the Evil Queen and Cruella de Vil, Mal begins questioning about being good and evil. Ultimately, the villain kids fail to retrieve the wand after Jay accidentally sets off the alarm and they escape.
On their first day, Jay is recruited for the school's tourney sports team. Carlos realizes dogs are not dangerous and befriends the school's mutt. Evie becomes infatuated with Chad Charming, son of Cinderella and Prince Charming, who takes advantage of her by making her do his homework. Mal befriends Jane, daughter of the Fairy Godmother. Mal exploits Jane's insecurity in her own appearance to her personal advantage by pretending to befriend Jane and even using some magic to change Jane's hair making her look more beautiful. After hearing about Jane's hair change, Mulan's daughter, Lonnie, and other girls' ask Mal to change their hair too. Evie learns the Fairy Godmother will use the wand at Prince Ben's coronation ceremony and the entire school, including the villain kids, are invited. Ben visits and Mal asks him if she could be seated closer to the wand during the ceremony. Ben replies that only he, his family and girlfriend, Audrey, daughter of Aurora and Prince Phillip, will be allowed to be seated up front. Mal hatches a plan to become Ben's girlfriend in order to get the wand. While making a love spell in the form of a cookie, the group realizes the spell needs a human tear of true sadness for the love spell to be successful. Lonnie interrupts the group and reminiscences about the love she felt when her mother made cookies to make her feel better. She sheds a tear out of sadness when she learns that the villain kids have never known love — even from their own parents. Mal quickly snatches the tear and adds it to the cookie dough. Mal gives Ben the cookie and the love spell begins to take effect. Jay, Carlos, and Ben work together to win the tourney game and Jay is named MVP. Ben declares his love for Mal in a song and asks her to the coronation, angering Audrey and causing her to go with Chad, which in turn upsets Evie.
Chad has Evie's magic mirror taken away and Evie is forced to take a test without its aid. Evie gets a 'B+' on the test proving she is intelligent without needing the help of her mirror and she tells Doug, son of Dopey, who believed in her. Ben asks Mal on a date and Evie helps her get ready. While on the date, Mal and Ben get to know each other. Ben decides to go for a swim but Mal declines to join him. Mal begins to question whether she really does have feelings for Ben. When Mal doesn't see Ben surface from the lake, she jumps into the lake to find him, but she can't swim and when she starts thrashing around in the water, Ben helps her get out. Ben asks Mal if she reciprocates his feelings of love and she replies by saying that she doesn't know what love feels like. Ben says that he probably can teach her.
The villain kids video chat with their parents for Auradon Prep's Parents' Day because the villains are not allowed to leave the island. At Parents' Day, Ben introduces Mal to his parents as his new girlfriend, much to their reluctance and shock. There, Audrey's grandmother blames Mal about Maleficent's actions and Chad also adds to the scorn. Evie sprays Chad with a sleeping potion Mal had given her and he collapses. The villain kids leave the lunch and King Beast blames Ben for the turn of events. After the lunch, the other students, now including Jane, mock the villain kids angering Mal to undo Jane's hair and threatening to do the same to the other girls. The group reluctantly plan to steal the wand.
The day of the coronation arrives and Mal gives Ben a cupcake with the anti-love spell. He reveals he knew all along because the spell was broken during their first date when he swam in the Enchanted Lake, which washed away the spell. In panic, Mal asks if he had been faking his feelings for her since then, but he tells her that his feelings are genuine as he entrusts her with his signet ring. Ben believes Mal gave him the love spell because she had a crush on him and didn't trust it could happen on its own. During the coronation ceremony, Mal contemplates whether she should get the wand for her mother, or be the better person Ben expects her to be. Suddenly, the wand is snatched up by Jane who wants to use it to give herself the magical makeover her mother won't allow. Unable to control the magic, Jane accidentally breaks the barrier around the Isle of the Lost. Sensing the barrier now gone, Maleficent takes her staff and magically flies away in dark smoke. Mal manages to pry the wand from Jane to fulfill her mother's wishes, but Ben convinces Mal she is good and that she and her friends should follow their hearts, not their parents' evil ways. Returning the wand to Fairy Godmother, Mal admits she loves her friends and wishes to stay at the school to be with Ben because it makes her happy. Maleficent arrives, renders everyone at the coronation still except for her and the villain kids, angrily saying Mal failed them, and takes the wand from the frozen Fairy Godmother. Mal tries to convince her mom to stop, but Maleficent turns into an enormous dragon and attacks them. Mal uses a spell and defeats Maleficent by shrinking her down to a small lizard, equivalent to amount of the love in her heart. Everyone unfreezes and the villain kids resolve to be good. In the end, the whole cast sing and dance at the coronation after-party. But Mal gives the audience a sly smile and flashes her green eyes, hinting that it is not the end of the story.
- Mal - (Dove Cameron) daughter of Maleficent.
- Jay - (Booboo Stewart) the son of Jafar.
- Evie - (Sofia Carson) daughter of the Evil Queen.
- Carlos De Vil - (Cameron Boyce), the son of Cruella De Vil.
- Prince Ben - (Mitchell Hope), son of Belle and the Beast and soon to be king of Auradon.
- Princess Audrey - (Sarah Jeffery), daughter of Aurora and Prince Phillip.
- Prince Chad Charming - (Jedidiah Goodacre), son of Cinderella and Prince Charming.
- Lonnie - (Dianne Doan), daughter of Fa Mulan and Li Shang.
- Jane - (Brenna D'Amico), daughter of the Fairy Godmother.
- Doug - (Zachary Gibson), son of Dopey.
- Maleficent - (Kristin Chenoweth) from Sleeping Beauty, Mal's mother, the leader of the villains and the main antagonist.
- Jafar - (Maz Jobrani) from Aladdin, Jay's father, who owns a junk shop on the Isle of the Lost.
- The Evil Queen - (Kathy Najimy) from Snow White and the Seven Dwarfs, Evie's mother.
- Cruella De Vil - (Wendy Raquel Robinson) from One Hundred and One Dalmatians, Carlos's mother.
- Queen Belle - (Keegan Connor Tracy) from Beauty and the Beast.
- King Beast - (Dan Payne) from Beauty and the Beast.
- Queen Leah (Judith Maxie) from Sleeping Beauty, the mother of Princess Aurora and the grandmother of Princess Audrey.
- Fairy Godmother - (Melanie Paxson) from Cinderella, the headmistress of Auradon Prep.
- Snow White - (Stephanie Bennett) from Snow White and the Seven Dwarfs, a local news anchor who reports on the activities at Auradon.
- Coach Jenkins - (Reese Alexander) the gym teacher at Auradon Prep who is the coach of its tourney team.
- Mr. Deley - (Jonathan Holmes) a science teacher at Auradon Prep.
At the 2015 D23 Expo, it was confirmed that a sequel is being made. Josann McGibbon and Sara Parriott were confirmed on October 15, 2015 to return as the writers, as well as being the executive producers.
- Keegan Connor Tracy, who plays Belle, also plays the Blue Fairy/Mother Superior in Once Upon a Time.
- Cameron Boyce got his frost tips just for this movie.
- Sofia Carson and Dove Cameron used wigs during filming.
- This is the first time that the Classical Disney film canon united in a feature film.
- As the villain kids progress from bad to good, the changes are reflected in their attire. They start out in their Isle of the Lost outfits, slowly decreasing in rebellious imaging, and finally to their coronation outfits and party clothes worn during "Set It Off".
- This would've been the second time Dove Cameron and Cameron Boyce worked together. The first time was in Dove Cameron's show, Liv & Maddie.
- This film contains many references and allusions to previous and current Disney franchises.
- The video game Carlos plays when the group first arrives to Auradon was originally created for the Disney XD original series Aaron Stone.
- Auradon Prep's motto is "Goodness doesn't get any better."
- During Rotten to the Core, if one looks closely behind to the group's dancing, the can see another "Long Live Evil" tag with Cruella's outline. And when you look behind Jay you can see the Jafar version of Long Live Evil.
- If one examines the stained glass windows of the church where the coronation is held, the images include Quasimodo, Snow White, Ariel, Aurora, Belle and Beast, Alice, Fa Mulan, Li Shang, Tiana, various princes, and what appears to be Kristoff. The last image suggest Arendelle is part of Auradon.
- 12.2 million people watched the premiere.
- Mitchell Hope almost quit acting before auditioning for the role of Ben in Descendants.
- 18.2 million total viewers (so far) have watched Descendants.
- Sofia Carson, who plays Evie, originally auditioned for the part of Audrey.
- Descendants is the #5 cable movie of all time.
- In "Set it Off" a lyric in the song was "We got the keys. The kingdom's ours." which Jay and Audrey sang. And Audrey is the daughter of Aurora and in Sleeping Beauty there is a lyric in a song "I got the keys to the kingdom."
- Dude, the male dog that Carlos becomes attached to, is actually a female dog named Paisley in real life.
- Kenny Ortega saw 600+ actors before casting Mitchell Hope as Prince Ben.
- Dove Cameron was the first person cast in this movie.
- Carlos and Dude (the dog) matched outfits after they met.
- If you look closely during the coronation, the parents of Audrey (Aurora and Phillip), Chad (Cinderella and Prince Charming), Lonnie (Li Mulan and Li Shang), and Doug (Dopey) are present.
- There was originally going to be a character named Aziz, son of Aladdin and Jasmine but was cut out for unknown reasons.