The House Bunny has a similar storyline to Legally Blonde, but it is slightly different. In The House Bunny, Shelley Darlington (Anna Faris) is Playboy Bunny living the life of luxury in the Playboy Mansion. The day after her twenty-seventh birthday, she finds a note asking her to leave because she is now too old. She happens to stumble upon a group of girls who remind her of herself. She tries to bond and share their home with them, but was not aware that they are members of the Phi Iota Mu. She learns about being a house mother, who live with the sorority sisters and watch over them. Although the Phi girls did not have one, they declined her. They suggested that she try to be the house mother for the Zeta Alpha Zeta sorority.
The members of the Zeta house are plain, socially awkward, and appear to be very physically unattractive. At first they rejected her, but after they saw that she was able to attract boys and friends, they changed their minds and allowed her to be their new house mother. As she took her role as the house mother, the Zeta girls told her about how the university was threatening to terminate them because they could never reach the required quota of thirty pledges. Shelley had the skills and experience that could help them gain popularity and finally reach the quota of pledges. Taking her place, Shelly begins to think of all types of activities they can do to raise money.
Shelley meets an intellectual, selfless guy named Oliver (Colin Hanks), which she begins to like. However, her flirty skills did not seem to work with him. She also gives the girls a makeover and lessons on how to attract a guy's attention. They are also viewing and choosing prospective pledges, but realize how judgmental they had become, and accused Shelley of encouraging this change. The Zetas decide to make themselves over again, taking Shelly's advice but also being themselves. As Lily (Kiely Williams) is mailing out the invitations, an attractive boy distracts her and a jealous Phi girl throws all the Zeta invitations in the trash. At the Pan-Hellenic meeting, Shelley gives a sincere speech and thirty students in the audience agree to pledge Zeta. Oliver, then agrees to go out with her again and try to get to know the real her.