McFadden, 24, has already swept 26.2-mile races in Boston, Chicago and London. She completed her marathon "grand slam" with a time of 1:59:13 at the New York City event.
"I can't believe it @INGNYCMarathon!!!!!!" she tweeted Sunday after her victory.
“A few times during the race, I hit a few bumps, and I was like, ‘Oh no,’” McFadden told The New York Times. “I just quickly looked at my tires and saw they were still rolling.”
McFadden, who will graduate from the University of Illinois with a degree in human development this December, beat her second-place competitor by 3:41.
“I’ve had an incredible year,” she told NBC Sports. “It’s taken me a long time to get where I am. I didn’t just wake up and this all happened.”
Born with spina bifida that paralyzed her from the waist down, McFadden lived in a Russian orphanage until she was adopted at age 6 by American Deborah McFadden, the director of the International Children’s Alliance.
Tatyana visited the St. Petersburg orphanage last year, gifting its director with her gold medal from the 2010 New York City Marathon.
"It was a good way to say thank you for keeping me safe for as long as possible and for keeping me alive as long as possible and a chance to show them how strong I am and the things I'm doing in life. It was an amazing experience," she told USA Today.
What's next for McFadden? Skiing, according to John Farra, the U.S. Paralympic director of Nordic skiing, who said the champion racer will compete in a Nordic skiing World Cup race for the U.S. this coming December.