Shatner, who played Captain James T. Kirk on the 1960s TV show, will travel as Blue Origin's invited guest with two businessmen who are paying customers and a company executive, Audrey Powers, the vice president of mission and flight operations.
Liftoff of the New Shepard rocket and capsule is planned at 10 a.m. EDT from the company's spaceport about 160 miles east of El Paso. The attempt will be the second crewed mission for Blue Origin, after Bezos flew July 20 with three crew members.
The paying passengers are Chris Boshuizen, a former NASA engineer and co-founder of San Francisco-based satellite company Planet Labs, and Glen de Vries, a French software firm executive and co-founder of New York clinical trials technology firm Medidata.
Shatner, 90, has been reminding people that he's never been to space before, despite the many trips his character made during 79 episodes of the television series aboard the USS Enterprise. He will become the oldest person to ever fly to space.
"I'm Captain Kirk, and I'm terrified of going to space," he told audience members during a New York Comic-Con panel Thursday. "You have three minutes to look into the vastness of space and the beauty of this oasis of Earth, and ... my only hope was I wouldn't see somebody else looking back."
"We're inseminating the space program," Shatner joked.
"I'm looking forward to the whole thing," he added. "I was there last week, rehearsing -- training I think is what they call it -- but I think it was rehearsal. I told them I want to go warp speed, and they said what?"
The mission, like all New Shepard flights, will ascend to about 62 miles above Earth, clearing the Karman Line that denotes the international definition of space.
Shatner said he's looking forward to the brief weightlessness at the peak of the flight before the capsule descends through the atmosphere and lands under parachutes not far from the launch pad in West Texas.
The inclusion of Shatner not only notches another record in spaceflight -- for oldest space flyer -- but it also brings a white-hot publicity spotlight to the mission, said Alan Ladwig, a former NASA employee and current adviser of a spaceflight training company, Virginia-based Star Harbor Academy.
"So they've been able to package this mission in an exciting way because of the popularity of Star Trek. I think it's quite a brilliant marketing move," Ladwig said.
He said Shatner and all passengers on such commercial spaceflights still sign waivers exempting the company from any liability should something go wrong.
"They've all worked with insurance companies to get as tight of a waiver as you could get," Ladwig said. "But, at the end of the day, I was told, you know, this waiver is as good as the next lawyer who takes you to court."