Kyla Ebbert said a Southwest employee asked her to leave her seat while the plane was preparing to leave San Diego's Lindbergh Field on July 3.
Ebbert, a student who was headed to Tucson for a doctor's appointment, said Friday on NBC's "Today" show that the employee told her she would have to catch a later flight.
"You're dressed inappropriately. This is a family airline. You're too provocative to fly on this plane," she quoted the employee as saying.
"I said, 'What part is it? The shirt? The skirt? Which part?' And he said the whole thing."
Ebbert was eventually allowed back on the plane after offering to adjust her sweater but said she was humiliated and embarrassed.
"I felt like everybody was staring me. They had all heard him lecturing me," she told "Today" show host Matt Lauer. She appeared on the show in the same short white skirt, white shirt and green sweater that she said she wore on the flight.
Chris Mainz, a spokesman for the Dallas-based airline, said a customer service supervisor asked Ebbert to leave the plane and addressed her in the walkway leading back to the terminal, "away from the other customers."
The employee felt the outfit "revealed too much" but was placated after Ebbert made adjustments that included covering her stomach, Mainz said.