Allison "Sonny" Munroe (Demi Lovato): The newest member of So Random!, she is from Middleton, Wisconsin. In the first episode, when Sonny was called in to be on So Random!, she might have taken the job of the former cast member Mandy, who has been only mentioned once in the first episode. Friendly and caring towards those around her, she is known as the nice girl of the group and does her best to help other people with their problems and achieve her dreams, earning mixed results. Sonny is friends with Nico, Grady, Zora and has an on-and-off friendship with Tawni. She also has a love/hate relationship with Chad Dylan Cooper, but as she gets to know him better she starts to develop a major crush on him. However, she is in constant denial about it to everyone and tries to keep it a secret.
Tawni Hart (Tiffany Thornton): A spoiled, manipulative and bratty cast member of So Random!, Tawni is obsessed with fashion, her looks, and her style and hair. She becomes upset if she does not get her way. Although she dislikes Sonny at first because she doesn't want to share her spotlight, she later accepts her even though their conflicting personalities occasionally cause disagreements. Tawni is probably the only person who knows Chad likes Sonny. Despite their rocky beginnings, she has since begun to care about Sonny as a friend, and is often seen giving her advice. She has been an actress since her first diaper commercial.
Chad Dylan Cooper (Sterling Knight): The teen heartthrob of Tween Weekly and MacKenzie Falls, as well as being the fremeny of Sonny and the cast of So Random!. Chad is mostly very self-centered, but at times can be very sweet and kind. He is probably the only cast member of MacKenzie Falls who is not very mean. Though most people accuse him of being a jerk, other people think of him as cute and popular. Chad originally has a love/hate relationship with Sonny Munroe, but eventually develops a crush on her. However, like Sonny, he denies that they have anything going on between them, though has been seen twice getting jealous when Sonny gets involved with another guy (Episodes "Sonny With A Chance Of Dating", and "Sonny In The Kitchen With Dinner"), and it seems like he wants Sonny to know that he has feelings for her.
Nico Harris (Brandon Mychal Smith): One of the primary cast members of So Random!, Nico is Grady's best friend and they always do wacky things together. Like shown in episodes such as "Three's Not Company" and "Sonny With a Chance of Dating" - where him and Grady find a way of troubling Murphy. He always comes up with ideas that later turn crazy as they should be. Nico tries to impress girls in unique ways but always messes up. He was on a one-man show called NICO. His dad is a lawyer.
Grady Mitchell (Doug Brochu): A cast member of So Random!, Grady is best friends with Nico. He is also wacky and always eager to eat. Together, he and Nico hatch plans such as making money by selling the other cast members' trash on the Internet. On the Disney Channel site, it says that he is from Orlando, Florida.
Zora Lancaster (Allisyn Ashley Arm): The youngest cast member of So Random! at 11 years old, Zora has a genius IQ and is the smartest member of the group and is known to be "the weird one" because Zora has a quirky personality and always seems to be up to a something suspicious. She is a prankster (shown in "You've Got Fanmail"). Zora, Tawni, and Sonny all share one room but Zora prefers to hide up in the air vent and the sarcophagus eavesdropping on private conversations. Zora is the only So Random! cast member who was absent on some episodes.
Connie Munroe (Nancy McKeon) is Sonny's mother. She is a bit strange, but gives good advice and cares a lot for Sonny, always wanting the best for her and is very supportive. She is happy that Sonny is on the show, but wants her to keep her priorities in order and keep her school work satisfactory. (First appearence: "Sketchy Beginnings")
Marshall Pike (Michael Kostroff) is the executive producer of So Random! and MacKenzie Falls. He also seems to be optimistic most of the time. He lives with his mother, and has another toe on his foot's side. In the episode "The Heartbreak Kids", he and Ms. Bitterman start a relationship. He seems to be unaware that So Random! and MacKenzie Falls are rivals. (First appearence: "Sketchy Beginnings")
Portlyn (Jillian Murray) is a cast member of MacKenzie Falls. She is the rich mean girl of Mackenzie Falls and her character has the same name as her own in the drama. Portlyn is also shown to be a quite dumb at times. She always wears the MacKenzie Falls cast uniform. (First appearence: "West Coast Story")
Joy Bitterman (Vicki Lewis) is the teacher for the cast of So Random!, whose last name reflects her personality. She claims she has not laughed since she left the Navy, which may explain why she is so tense and bitter. She lives alone with her 16 cats. In the episode "The Heartbreak Kids", Sonny sets her up with Marshall, and they start a relationship. (First appearence: "Cheater Girls")
Murphy (Steve Hytner) is the offbeat security guard who works by the So Random sets door. He takes his job a little too seriously and enjoys taking Nico and Grady's pizzas; biting into each slice and putting them back in the box. It is unknown why he hates Nico and Grady so much. (First appearence: "Three's Not Company")
Josh (Brent Tarnol) is the mailman for So Random!. He is shown to have crush on Sonny. (Appeared in "You've got Fanmail")
Lucy (Eden Sher) is Sonny's best friend from Wisconsin. (Appeared in "Three's Not Company")
Sharona (Elisa Donovan) is the rude celebrity blogger who says bad things about celebrities on her blog called "Sharona Knows". (Appeared in "Poll'd Apart")
Monke (Lily Holleman) is Sharona's assistant. Sharona calls her "Monkey" because Monke's name sounds like Monkey. She is shown to be afraid of Sharaona and Sharona mostly needs Monke to get her lattes. (Appeared in "Poll'd Apart")
James Conroy (Kelly Blatz) is Tawni's ex-boyfriend. His catchphrase is "You'll never take me alive!". (Appeared in "Sonny With a Chance of Dating")
Dakota Condor (Genevieve Hannelius) is the daughter of the founder of Condor Studios who is obssesed with Chad Dylan Cooper. She is actually evil (mentioned from Zora) and seems to disobey her father because she said that she's been crushing on a star when she's certainly not allowed to. (Appeared in "Sonny and the Studio Brat")
Mr. Condor (Daniel Roebuck) is the head of the "Condor Studio". He cancles the show of any actor who tics him off. He also doesn't know that his own daughter is evil. (Appeared in "Sonny and the Studio Brat")
Hayden (Robert Adamson) is the new assistant on the "Condor Studio" and Tawni's crush. (Appeared in "Sonny in the Kitchen with Dinner")