In December, Trevor Noah, a 31-year-old comedian, made his debut as an on-air contributor on “The Daily Show With Jon Stewart,” offering his outsider’s perspective, as a biracial South African, on the United States.

“I never thought I’d be more afraid of police in America than in South Africa,” he said with a smile. “It kind of makes me a little nostalgic for the old days, back home.”

Now, after only three appearances on that Comedy Central show, Mr. Noah has gotten a huge and unexpected promotion. On Monday, Comedy Central announced that Mr. Noah would be the new host of “The Daily Show,” succeeding Mr. Stewart after he steps down later this year.

The network’s selection of Mr. Noah comes less than two months after Mr. Stewart, 52, revealed on Feb. 10 that he was leaving “The Daily Show” after a highly successful 16-year run that transformed the show into authoritative, satirical comedy on current events. (An exact timetable for Mr. Stewart’s departure has not been decided, Comedy Central said.)