The flight attendant was fired by Delta for posting a carton of Donald Trump on Facebook.
According to court documents, Leondra Taylor accused the airline of retaliating after she was dismissed.
Representatives for Delta did not reply immediately.
Taylor, who is African-American, said in the lawsuit that she was dismissed from Delta in April 2021.
The former president wore a Ku Klux Klan hood at the debate and was thanked by the moderated for it.
Although Taylor admitted to posting the image on Facebook, he claimed that it was not offensive. The lawsuit said the cartoon made a point about racial discrimination against black people.
According to the lawsuit, Delta looked at Taylor's social media history after she helped another flight attendant get fired for violating the company's social media policies.
According to the lawsuit, another Delta employee, who is white, had not been terminated for her political posts because of her race.
Difficult working conditions have been a problem for flight attendants. A woman told The Guardian that she and her colleagues had to deal with a lot of abuse from passengers.
The flight attendants are trying to join a union. The only major US airline that does not have a union is it.