CNN President Jeff Zucker has resigned from the cable news network, citing his failure to disclose a consensual relationship with a close colleague, according to an email he sent to staff on Wednesday.

“I came to CNN on January 28, 2013. Together, we had nine great years. I certainly wish my tenure here had ended differently. But it was an amazing run. And I loved every minute,” he wrote.

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CNN President Jeff Zucker has resigned from the cable news network, citing his failure to disclose a consensual relationship with a close colleague, according to an email he sent to staff on Wednesday.

“I came to CNN on January 28, 2013. Together, we had nine great years. I certainly wish my tenure here had ended differently. But it was an amazing run. And I loved every minute,” he wrote.

A triumvirate of CNN executives will lead the network on an interim basis, according to people familiar with the situation. Michael Bass, executive vice president of programming, Amy Entelis, executive vice president for talent, and executive vice president Ken Jautz will be in charge of CNN until a new executive is named, the people said.

The colleague Mr. Zucker referred to is Allison Gollust, an executive vice president and chief marketing officer at CNN. In a statement, Ms. Gollust said that she and Mr. Zucker have been friends for over 20 years and said that the relationship changed during the Covid-19 pandemic.

“I regret that we didn’t disclose it at the right time,” Ms. Gollust said. “I’m incredibly proud of my time at CNN and look forward to continuing the great work we do everyday.”

‘I certainly wish my tenure here had ended differently,’ Jeff Zucker said in an email to staff.

Photo: Mike Coppola/Getty Images

In his email to CNN employees, Mr. Zucker said his relationship with Ms. Gollust “evolved” in recent years. He said he was required to disclose it when it began, and was wrong not to do so.

Some senior executives at CNN didn’t see Mr. Zucker’s abrupt departure coming, a person familiar with the matter said. Top CNN executives, including Ms. Gollust and Mr. Bass, were scheduled on Wednesday afternoon to meet with Jason Kilar, chief executive of CNN parent WarnerMedia.

Mr. Zucker disclosed the relationship with Ms. Gollust to WarnerMedia, a unit of AT&T Inc., during an investigation into former CNN host Chris Cuomo, the person familiar with the matter said. Mr. Cuomo was fired by CNN in December after the investigation found he improperly helped his brother, former New York Gov. Andrew Cuomo, respond to accusations of sexual misconduct.

Mr. Zucker’s departure comes as AT&T is preparing to spin off WarnerMedia and merge it with Discovery Inc. to form a new company, Warner Bros. Discovery. Mr. Zucker had indicated he planned to stay at CNN at least through the closing of the deal.

A former wunderkind producer of NBC’s “Today” show, Mr. Zucker rose through the media industry’s ranks over a three-decade-plus career. He became CEO of NBCUniversal, leaving after Comcast Corp. took control in 2011.

After joining CNN in 2013, Mr. Zucker quickly put his stamp on the network, reshuffling the anchor lineup and hiring journalists such as Jake Tapper, Alisyn Camerota, Mr. Cuomo and Brian Stelter. The network enjoyed a ratings surge during the Trump years, as Mr. Zucker steered coverage that was critical of the former president. More recently, CNN’s viewership has fallen off amid a wider decline in cable ratings.

As CNN’s business head and de facto programmer-in-chief, Mr. Zucker has been a hands-on leader, running daily news calls and spearheading contract negotiations with anchors. His departure leaves a hole at the network, which is preparing to launch an ambitious direct-to-consumer streaming service. In 2019, Mr. Zucker was promoted to take on oversight of WarnerMedia’s sports properties, in addition to his role at CNN.

Write to Benjamin Mullin at Benjamin.Mullin@wsj.com