The Nigerian woman, Queen Obioma, said she and her children suffered unnecessary embarrassment when a flight crew ordered them off a plane in Houston, Texas, in 2016 after the passenger complained to a pilot that she was "pungent" and he was uncomfortable flying on the same plane as her, according to the lawsuit.
The suit was filed on Friday in federal court in Houston and asks for damages of more than $75,000.
Obioma says she was taking her two children to Ontario, Canada, to enroll in a school and had boarded the second-leg of a three-plane flight to their destination when they were forced off the jet, according to the suit.
"United has no legitimate reason or justification to remove [Obioma] from the flight but for racial prejudice and insulted [her] by stating that Ms. Obioma stank," according to the lawsuit.
In a statement to ABC News on Sunday, the airline said, "United does not tolerate discrimination of any kind and will investigate this matter."
"We have not yet been served with this suit and due to the pending litigation involved, we’re unable to provide further comment," a spokeswoman for the airline told ABC News.
In a statement to ABC News on Monday, Obioma's lawyer, Nwadi Nwogu, said the "lawsuit speaks for itself."
"For now we will decline further comment except to say that we have a responsibility to our client to seek redress for the unfair, undeserving and [inhumane] treatment she and her children received from United Airlines," Nwogu's statement reads.
According to court papers, Obioma says the incident occurred on March 4, 2016, about two hours after she and her children arrived at George Bush Intercontinental Airport in Houston part way into a 16-hour flight from Lagos, Nigeria, to Ontario.
She said when she boarded United Flight 404 from Houston to San Francisco, she found a man sitting in her business-class seat and refusing to budge.
"She politely informed the white male that he was occupying her assigned seat but he ignored her," according to the suit.
Obioma told a member of the flight crew, who asked the man to move to his assigned seat, the suit says. But when he refused to move, Obioma was asked to take another seat in business class and she complied.
As she placed her carry-on luggage in the overhead compartment, she noticed the man who was in her original seat go into the cockpit, according to the suit.
Obioma said she went to the restroom while people were still boarding and when she came back, she found the same man blocking the aisle.
She said she asked the man, who was not identified, to let her get by, saying "excuse me" three times before he finally gave her enough room to squeeze by him, the suit claims.
As soon as she took her seat, a flight attendant "ordered her out of the aircraft stating that her attention was required because someone was waiting to speak with her outside the aircraft," the lawsuit reads.
Once outside, Obioma was told she was being removed from the flight. She protested and showed the flight attendant her boarding pass, the suit says.
The flight attendant told her "the pilot personally requested that Ms. Obioma be ejected from the aircraft because the white man sitting around her in the business class cabin was not comfortable flying with her because she was 'pungent,'" the suit says.
"Ms. Obioma asked [the flight attendant] what 'pungent' meant and he answered that she smelled," the suit states.
"At that point, Ms. Obioma was lost, confused and disoriented. Her mind went blank and she was utterly befuddled," according to the suit.
She argued that she had to make a connecting flight in San Francisco to Ontario, and had a meeting at her children's school that they would miss if not allowed to take the flight.
The suit claims Obioma wasn't allowed back on the plane to get her children seated in economy class or to retrieve her carry-on luggage.
A flight attendant, instead, escorted Obioma's two children off the plane.
"Ms. Obioma watched her minor children marched out of the aircraft like criminals, confused and perplexed and she slumped," according to the legal papers. "She sobbed uncontrollably for a long time."
Obioma and her children were delayed five hours before they could catch another flight, the papers say.
The delay caused Obioma to miss the scheduled appointment at her children's school. She had to reschedule and extend her stay, adding additional expenses to her trip, the suit claims.
Obioma alleges United "wrongfully" singled her and her children out because of their race and "punished them publicly because a white man did not want them on the plane," according to the suit.