Chestnut, 32, had won eight titles in a row before losing to 24-year-old Matt Stonie, known as "The Megatoad, last year. In 2013, he set the record with 69 hot dogs in 10 minutes. Stonie ate 62 hot dogs last year, two more than Chestnut. They both are San Jose, Calif., residents.
In a qualifying event last month, Chestnut ate 73 1/2 dogs.
Stonie, who holds 14 eating world records, was the first winner not Chestnut or Takeru Kobayashi since 2000.
Chestnut said Stonie "woke up the sleeping giant" when he beat him out last year.
"Last year was rough," Chestnut told the crowd. "This year was the best ever."
Stonie said there were "no excuses" for his loss. He said Chestnut did an amazing job.
Earlier in the women's event, Mikie Sudo, of Las Vegas, successfully defended her title by eating 38 1/2 dogs, beating out three-time winner Sonya "The Black Widow" Thomas, of Alexandria, Va., with 35.
The contest has occurred each July 4 in Coney Island since 1916, the year Nathan Handwerker opened the legendary restaurant.
Several thousand watched the eaters on an elevated stage.
One man held a sign that read: "Make America Eat Again," a play on presumptive Republican presidential nominee Donald Trump's campaign slogan, "Make America Great Again."