Candy is shy, insecure and faint hearted girl largely due to being put down by popular girls like Pacifica Northwest, and for this reason tends to hang out with other girls that are rejected by individuals. She enjoys spending time with her friends, whether the activity is going to a party, reading magazines about boys, having sleepovers, trick-or-treating, reading romance novels, or simply hanging out. She likes coming up with ways to innovate the human body, such as taping forks to her fingers in order to consume popcorn. Mabel describes her as very cheerful, and she expresses a humorous side. She express a love of photography, taking various pictures with her cell phone that she may post on the internet. She finds Waddles to be adorable, as seen in "Summerween", where in the credits, she takes pictures of Waddles with Mabel and Grenda.
Candy is a young girl with straight jet-black hair and wears glasses. She has been seen wearing a striped jade shirt, a purple skirt, white socks, black shoes, and a pink backpack. Her eyes are black and her skin is fair. Along with this, she has black stud earrings.
At some point, Candy became good friends with Grenda. The two go to the Party at the Mystery Shack together in "Double Dipper". Here, they meet and befriend Mabel after she introduces herself. Shortly after Mabel inquires as to why Candy has forks taped to her fingers, she demonstrates how she uses them to eat popcorn, and calls it "Improvement of human being." Mabel then comments that she has "found her people". Later, when Pacifica Northwest arrives, Candy tells Mabel who the girl is, and she and Grenda cheer their new friend on in her competition against Pacifica. After Pacifica wins the contest by bribing Old Man McGucket, Candy and Grenda decide to stay and sleep over with Mabel, as opposed to going to Pacifica's after party like most of the other attendees. It is presumed that the trio spends the night dancing and reading magazines about boys.
She appears again in "Summerween", dressed as a peppermint for trick-or-treating; however, her and the others' motives change after the Summerween Trickster threatens to eat them if they fail to secure five hundred pieces of candy for him. Thus, she, Grenda, Mabel, Dipper and Soos begin their trick-or-treating. At a point, after Dipper accidentally sends all their treats but the final one into a stream, the gang quickly races to prevent Old Man McGucket from blowing out the candle in his jack O' Melon to buy them more time, only to extinguish it with their sighs of relief. Then, the Trickster shows up and prepares to eat them upon learning they have not met his request, but Soos drives straight through and destroys the Trickster, but the Trickster reassembles and chases the group into the Summerween Superstore. They try to escape by disguising themselves in various costumes, and end up battling the monster after he eats Soos. Once they are saved by Soos eating the beast, they return to the Mystery Shack, where they enjoy candy, watch movies and celebrate pure evil.
In "Carpet Diem", Candy and Grenda go to Mabel's house to have a sleepover. Later, they find Dipper in Mabel's body and take him upstairs for a second sleepover. After Dipper and Mabel switch back, Mabel tells the girls about the carpet's magical properties, and Candy switches bodies with Dipper. Candy also switches bodies with several other people like Sheriff Blubs and Mabel. In the end, everyone ends up back in their own bodies.
In "Boyz Crazy", Candy, Mabel and Grenda attend a Sev'ral Timez concert. Afterwards, they sneak backstage, discovering that the band are actually clones being held as slaves by their manager. They release the boys and bring them to the Mystery Shack. Soon after, Mabel becomes highly possessive of them, forcing Candy and Grenda away. Eventually, Mabel decides to let the band go, and the three release them into the wild, in which Candy remarks they will probably not survive.
In "Gideon Rises", she and Grenda reappear as Dipper and Mabel prepare to leave Gravity Falls. The two girls are seen comforting each other. They do not appear after that, not even when the rest of the town gathers around the remains of the Gideon-bot at the end of the episode.
She appears in "Mabel's Guide to Fashion" though she is not seen while Mabel and Grenda do flash makeovers. At one point she and Mabel are shown scribbling on each others' faces.
In "Mabel's Guide to Colors", she participates in Mabel's survey of everyone's favorite colors. Later, when Mabel has declared a color emergency, she calls upon Candy, Grenda, and Dipper for ideas on how to make Stan see a rainbow. Candy quickly draws up a plan to reflect a rainbow from the falls into Stan's office window, and everyone agrees with it. She and Dipper stand in the back of Soos's truck and use a large mirror to reflect the rainbow into Stan's office window. Unfortunately, this creates a painfully intense rainbow-colored light beam that hurts Stan's eyes and also sets fire to some things in his office.
- Candy's last name is Chiu, a pun on "candy chew".
- In the ComicCon 2013 panel Alex Hirsch stated that Candy Chiu and Grenda are Mabel's "life long friends".
- Her favorite color is "Magic Vision Poster".
- In the episode "The Love God", it is implied that Mabel hopes to establish a romantic relationship between Dipper and Candy. Currently, though, it is officially unknown if Candy has such interest in Dipper.
- It was revealed in "Roadside Attraction" that Candy had/has a crush on Dipper, but lost it by the end of the episode.