As former CEO of Expedia for just over 12 years, Khosrowshahi says the decision wasn't easy.
"This has been one of the toughest decisions of my life," he writes.
"I've been here at Expedia for so long that I've forgotten what life is like outside this place," Khosrowshahi writes.
Surprisingly, despite having a 94 percent approval rating as one of the highest-rated CEOs on Glassdoor, the tech pioneer hasn't always felt confident in his ability to lead.
"Early on, I didn't know what I was getting into," Khosrowshahi says in a profile as a 2013 Ernst & Young (EY) Technology Entrepreneur of the Year. "For the first year when I was running the company, I wasn't a particularly good CEO."
In the interview, he discusses the moment he gained confidence in his ability to effectively lead, bringing up the story of a young engineer who offered him some advice. "Dara, you're telling us what to do, but you're not telling us where to go," he recalls in the EY interview.
"That really rung a bell for me," Khosrowshahi says, "where I was just telling people what to do but I wasn't laying the vision of here's where we've got to go."
"If you tell us where to go we'll do it," he recalls the young woman saying, "because we believe in you. We want to go there, tell us where to go and then we'll do it."
"That really shifted my view of what a CEO has to do," Khosrowshahi says. "A CEO of a multinational global company can't say what to do. You've got to plant the flag."
Expedia began as entrepreneur and Glassdoor co-founder Rich Barton's internal project at Microsoft into the billion-dollar online travel company. Khosrowshahi was 34 years old when Expedia later spun off from its parent company IAC/InterActiveCorp, the New York Times reports.
Although he wasn't a part of Expedia's founding team, he says in a 2013 LinkedIn post that he felt lucky "to be in the right place at the right time" with taking over as the company's CEO.
For the future, Khosrowshahi would do well to take his own advice as Uber's CEO. He writes that while at Expedia, the company has adopted a "culture of celebrating failure" because there is almost always "another chance to get up and try again."
"Taking big risks combined with having a team you believe in and that believes just as much in you as a leader make for long-term wins even in a game of inches," Khosrowshahi writes.
In his email to Expedia employees, Khosrowshahi comes to terms with the leap of faith he's taking on leaving the company after 12 years.
"the times of greatest learning for me have been when I've been through big changes, or taken on new roles," Khosrowshahi writes. "You have to move out of your comfort zone and develop muscles that you didn't know you had."
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This article has been updated.