The Washington-based spaceflight company didn't disclose the name of the person who purchased the seat. The winner will take the trip with Jeff Bezos and his brother Mark Bezos.
"The name of the auction winner will be released in the weeks following the auction's conclusion. Then, the fourth and final crew member will be announced -- stay tuned," the company tweeted.
Blue Origin opened the live auction Saturday afternoon, more than a month after it opened sealed online bidding.
Money from the winning bid will be donated to Blue Origin's foundation, Club for the Future, which seeks to inspire youngsters to purse careers in STEM.
Blue Origin plans to fly its first astronaut crew to space about the New Shepard on July 20. Whoever wins Saturday's auction will be on the crew.
Those who wish to bid on the Blue Origin seat must fit certain physical requirements, weighing between 110 pounds and 223 pounds and be between 5 feet and 6 feet, 4 inches tall. They must also be able to withstand up to 3Gs during ascent and 5.5 Gs during descent.
Blue Origin in April carried out what was expected to be its last test flight for the New Shepard rocket before carrying people. The goal is to allow true space tourism for anyone, said Kevin Sproge, Blue Origin's director of space architecture for New Shepard.
"You don't need to be a NASA astronaut, you don't need to be a trained engineer, we want artists and poets, teachers and scientists," he said.
The New Shepard capsule is outfitted with improved acoustics to dampen the roar during flight, better interior temperature regulation, crew display panels, and speakers with a microphone and push-to-talk button at each seat, the company said.
In 2001, California businessman Dennis Tito paid Russia's space agency $20 million to become the first tourist in space. The agency launched the millionaire to the International Space Station and brought him back to Earth.