Three girls attending the same private school meet in detention and bond over their love of music and hip hop dance. When they clash with queen bee Bambi Lockwood, the trio decide to challenge her and enter the yearly stun party.
The movie starts with each girl talking directly to the camera about how they ended up at Summerdale High. Amanda "Mandy" Rain rolls in on roller blades and talks about being stuck at a private school that creates "Martha Stewart cookie cutter types." Jacque Pynes states that she was taken from her hood and "shipped here by the man." Monica "Mo Money" finishes a call to Robert Cavalli while she uses the school bathroom as her personal vanity. Eventually, the three end up in detention: Mandy for rolling into a teacher holding a cake, Jacque for tagging the school sign, and Monica for locking people out of the bathroom and causing a fire hazard.
Mandy and Monica bond over their reasons for being put in detention while Jacque tries to ignore them. When Monica asks Jacque for her reason, the latter replies sarcastically which nearly starts a fight. The principal comes with her twin daughters and the hall monitor, Daisy and demands to know what is going on. Monica makes up an excuse to get Jacque out of trouble and the principal replies that since the three girls seem to want to stick together, she plans to have them room in the "VIP" room and to serve trash duty together. Jacque thanks Mandy for getting her out of trouble and sarcastically thanks Monica who boasts that she did most of the work.
As the girls pick up trash outside, they observe some of their classmates hanging out. All of them notice Collin Andrews, who is the best looking boy at their school who happens to be dating queen bee Bambi Lockwood. Mandy recollects meeting Collin earlier, only he ended up sneezing on her. Monica admits that she has a crush on him and admires Bambi as she is the pippest girl at school. In attempt to catch Collin's eye, Monica spills her bag by him and he rushes to help her. However, Bambi storms over from cheer practice and snaps at Collin to stop helping the "loser freshman with a major wanna-be-me complex." After she expresses her frustrations with the trio, she purposely spills her sports drink on Jacque's hoodie, prompting the latter to go after her. Daisy catches them and puts them back into the detention room, where the trio perform "Detention."
Daisy takes them to a trashed dorm room and leaves the girls to unpack. As they clean up and make the space personal to their tastes, Jacque notes that Collin seemed interested in Monica. Mandy admits that her crush is Justin Bieber while Jacque says that her dream guy is Soulja Boy. Jacque states that they need to deal with Bambi who is really getting on her nerves. Mandy suggests that they enter the stun party to show Bambi what they're made of and bribes Jacque to enter as one of the guest judges is Soulja Boy.
The next day at the club showcase, Bambi announces that sign-ups for the stun party are open. Jacque pushes to the front of the group and enters the trio. Bambi states that there is a fee of $100 per act and she looks at Monica, expecting her to pay for the group since her moniker is "Mo Money." Monica claims that she needs to have her accountant wire over the money tomorrow but she can definitely get the money for the entry. Bambi adds that she doubts that the trio are even on her level, which prompts Jacque to challenge her into a dance off to the song "What Goes Around." Daisy tries stop the dance off by blowing the whistle and someone throws food at her. In retaliation, she hits a table with a cooler filled with a sports drink and the contents spill over Bambi. The lunchlady yells at everyone to get to class and declares that someone will go to detention.
Monica calls her accountant from detention about wiring over the funds and throws in a request for her credit card limit to be extended before hanging up. Daisy comes in and states that the girls need to tighten up their dance moves if they want to beat Bambi. She demonstrates sharp, crisp moves before leaving to answer a call from the headmistress, leaving her keys behind. The girls take Daisy's keys and sneak into the art room to get supplies to fix up their room, singing "It's Just a Kiss."
Once the girls add the finishing touches to their room, Monica leaves to make a call, leaving her cell phone behind. She calls her mom to ask for the $100 to pay for the entry fee for the event, only to stop when her mom mentions being behind in payments again. Monica hangs up and runs into Collin who is practicing his guitar late at night, which he keeps secret from Bambi as she thinks musicians are uncool for her image. He apologizes for Bambi's behavior and Monica waves it away as nothing. Unbeknownst to them, Bambi has snuck in and is eavesdropping on their conversation. Collin leaves Monica in the library and she thinks about him, singing "Something about Him" with the other girls. Meanwhile, Bambi sneaks into the headmistress's office and searches for Monica's file for any incriminating evidence to humiliate her. She discovers that Monica is not really as rich as she claims she is and can only afford to attend Summerdale because she is on an academic scholarship.
The next day Bambi rounds up her posse and confronts Monica as she talks to Beyonce on her cell. Monica pretends that its a dropped call when Bambi asks to speak with Beyonce. Bambi snatches Monica's phone from her and gestures to one of her friends to film this. Bambi checks the phone and loudly announces that the phone was never in service, meaning that Monica is poor and that she is only here because of her high test score. Bambi gloats that Monica is nothing but trash and adds that she needs to stay away from her boyfriend. Monica runs off in tears while Jacque and Mandy get up in Bambi's face for hurting Monica. Monica cries and begins to sing "Not Just a Girl" while Bambi uploads the video on a social media site.
The video spreads around the school and Jacque and Mandy tell Monica that they don't care if she's rich or not. They get a knock on the door and Claire, Bambi's sidekick who filmed the incident comes in. Claire apologizes for siding with Bambi and pulls out some photos of Bambi with a plan to help get even. The girls print out calendars with doctored photos of Bambi looking her worst and sell them to earn money for the entry fee. The girls sing "Extra Extra" while they sell the calendars until Bambi finds out and flips. Bambi tells her father and the headmistress who punish the girls with permanent detention.
Bambi shows up to the stun party while the girls are stuck in detention. Monica blames herself for getting the girls into this mess while Jacque replies that they all got themselves into trouble because they wanted to. They break out of the detention room, tie up Daisy, and steal the golf cart to get the stun party. Bambi eyes Justin Bieber during his performance and falls for him, eagerly getting up on stage to dance with him to catch his eye. The stun party competition begins and Bambi watches as the twins then Collin perform before the judges. She claims that she's over Collin and would rather have Justin Bieber. Her group performs and impresses the judges.
Mandy, Jacque, and Monica are driving over when the golf cart runs out of gas. Kristina DeBarge gets up and performs for the stun party. The girls walk the rest of the way but make it too late as Bambi saunters out with the trophy and Justin on her arm. Bambi tries to single the girls out for sneaking out of detention and she insults Jacque with a racial nickname. Monica steps up and confronts Bambi, stating that she doesn't care about having money or being popular. Jacque adds that they should settle this with a dance off. The groups head outside of the Teen Island club and dance to "Get Like Me". Jacque throws in some impressive moves and the trio beats Bambi. Bambi blames her posse for losing and Collin takes her trophy to give to Monica and kisses her. Angry, Bambi storms up and tries to take back the trophy but is stopped by Claire, who has changed sides and threatens to create more doctored photos of Bambi. Bambi gives up and huffs away as the School Gyrls celebrate.
The film ends with the girls sitting out on the sidewalk with the trophy and they hug, happy to have met each other. A limo pulls up and Soulja Boy rolls down the window to congratulate the girls and says that Jacque has skills. Kristina DeBarge asks if they want a ride and they accept.