“We have made history tonight,” the 29-year-old told cheering supporters at her victory party in Queens, a big victory for a woman working in a Manhattan restaurant only a year ago.
She is the daughter of a cleaner and a father who died in his 40s, embodying a different generation of politician and shunning corporate donors.
On Tuesday, she signalled a deep ambition running beyond the confines of her constituency and thanked organisers for building a “larger movement for social, economic and racial justice in the United States of America” in a stirring speech that ended with confetti falling from the ceiling.
“If we are going to turn this ship around as a country it is not good enough to throw a rock at our neighbour’s yard, we’ve got to clean up our own house,” she said.
“There is nothing inherently noble about protecting a status quo that does not serve the needs of working class Americans.”
In a further sign that her dreams run big, she spoke of the galvanising power that her campaign had on other races around the country and vowed that hers would be the generation to flip the Republican state of Texas blue.
She is also the first person of colour to represent the safe Democratic seat in diverse Queens and the Bronx, which is largely immigrant.
When she beat incumbent Joe Crowley, she was moonlighting as a bartender.
Ocasio-Cortez once worked for the late Senator Ted Kennedy while studying economics and international relations at Boston University. She has worked with female entrepreneurs in Africa and in education.
She is a Democratic Socialist in the vein of failed 2016 presidential hopeful Bernie Sanders, on whose campaign she worked.
Ocasio-Cortez has compared the fight against climate change to the fight against Nazi Germany in World War II, calling it a “major existential threat” and has likened electing Democrats to ending slavery.
The right has branded her politics “dangerous” and she has also taken hits from centrist stalwarts, former senator Joe Lieberman saying her primary win seemed “likely to hurt Congress, America and the Democratic Party”.
“She is a really good candidate with good political instincts,” Jeanne Zaino, a political scientist at Iona College, has said.
“But we can’t forget the larger forces, there’s a real frustration … with the establishment,” she added. “I’m not sure she’d have won if her opponent wasn’t a leader of the Democratic Party.”