CNN Worldwide chief Jeff Zucker said that he will be resigning, with immediate effect.

Zucker said in a memo, “As part of the investigation into Chris Cuomo’s tenure at CNN, I was asked about a consensual relationship with my closest colleague, someone I have worked with for more than 20 years. I acknowledged the relationship evolved in recent years. I was required to disclose it when it began but I didn’t. I was wrong. As a result, I am resigning today.”

Zucker did not name his colleague in his statement, but the relationship is with Allison Gollust, the chief marketing officer for CNN.

It is understood that Gollust will remain at CNN.

In December, CNN fired host Chris Cuomo, the brother of former New York governor Andrew Cuomo, after an investigation into claims he was helping his brother defend against sexual harassment claims.

The relationship between Jeff Zucker and Gollust came up during the network’s investigation into the former anchor Chris Cuomo. “I was required to disclose it when it began but I didn’t,” he wrote in the memo to colleagues.

Jeff Zucker resigned on Wednesday as the president of CNN and the chairman of WarnerMedia’s news and sports division.

Mr. Zucker, 56, is among the most powerful leaders in the American media and television industries. The sudden end of his nine-year tenure immediately throws into flux the direction of CNN and its parent company, WarnerMedia, which is expected to be acquired later this year by Discovery Inc. in one of the nation’s largest media mergers.

Allison Gollust is CNN’s executive vice president and chief marketing officer and one of the highest-ranking leaders of the network. She is closely involved in major business and communications decisions.

Ms. Gollust said in a statement that she would remain in her role at CNN.

“Jeff and I have been close friends and professional partners for over 20 years,” she wrote. “Recently, our relationship changed during Covid. I regret that we didn’t disclose it at the right time. I’m incredibly proud of my time at CNN and look forward to continuing the great work we do everyday.”

Both Mr. Zucker and Ms. Gollust are divorced.