In a proposed class action filed on Tuesday in Los Angeles, Holly Ricketson said she bought a Wicked doll for her daughter, who then visited an adult entertainment website through the link provided by the toymaker.
Ricketson said her daughter showed her hardcore photographs from the website and both were "horrified" by what they saw, suffering emotional distress.
The plaintiff said she would not have bought the doll had she known of the mistake, and Mattel has not offered refunds despite recalling the dolls on November 11.
Mattel declined to comment on the lawsuit, but said in a statement that sales of Wicked dolls with correct packaging have resumed in stores and online. It has expressed regret for the error.
The El Segundo, California-based toymaker had intended to link purchasers to the WickedMovie.com website, not to a similarly named website for people at least 18 years old.
Mattel recommends the dolls for children aged four and up.
Tuesday's lawsuit seeks at least $US5 million ($A7.7 million) of damages for anyone in the United States who bought "Wicked" dolls whose packaging included the errant link.
It accuses Mattel of negligence, selling products unfit for sale, and violating California consumer protection laws.
Other products from Mattel include Barbie and Hot Wheels.
Wicked, from Universal Pictures, stars Cynthia Arivo and Ariana Grande.
It has grossed $US263.2 million ($A405.9 million) in the United States and $US360.3 million ($A555.7 million) worldwide since its November 22 release, according to Box Office Mojo.
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