The fast-moving national reckoning over sexual harassment in the workplace reached the highest level of television news on Wednesday when NBC fired Matt Lauer, the co-host of its most profitable franchise, the top-rated morning show “Today,” following an allegation that he made inappropriate sexual contact with a subordinate.

NBC News told its staff it was firing Mr. Lauer some 34 hours after the woman and her lawyer visited the network headquarters in Midtown Manhattan to share details of her interactions with Mr. Lauer with company executives. Earlier that day, she had also met with reporters from The New York Times but said she was not ready to discuss it publicly.

“On Monday night, we received a detailed complaint from a colleague about inappropriate sexual behavior in the workplace by Matt Lauer,” Andrew Lack, the NBC News chairman, said in a memo to the staff. “While it is the first complaint about his behavior in the over 20 years he’s been at NBC News, we were also presented with reason to believe this may not have been an isolated incident.”

Lauer joins a lengthening list of media figures felled by sexual misconduct charges this year. Besides Rose, they include Lauer’s former NBC News colleague Mark Halperin, former Fox News prime-time host Bill O’Reilly and National Public Radio newsroom chief Michael Oreskes. The New York Times suspended White House correspondent Glenn Thrush last week.

Messages to Lauer and his agent were not immediately returned.