SAN FRANCISCO — Dara Khosrowshahi’s family immigrated to the United States from Iran in 1978, when their country was convulsed by revolution. They were not particularly welcomed in America, and were broke.

“Every one of us cousins had a chip on our shoulders, having lost everything to the new Iranian government,” said Hadi Partovi, a cousin of Mr. Khosrowshahi’s. “We had a desire to build anew as entrepreneurs.”

Mr. Khosrowshahi, 48, is on the threshold of becoming one of the world’s most prominent entrepreneurs. On Sunday night, he was selected to be chief executive of Uber, the ride-hailing company that is the world’s most valuable start-up. The deal is almost official, according to the travel reservations site Expedia, which Mr. Khosrowshahi currently runs.

The news follows six months of extraordinary turmoil at Uber. Mr. Khosrowshahi will succeed Travis Kalanick, an Uber co-founder and the company’s driving force, who was forced to step down in June as the business was rocked by one scandal after another.