Kevin Tsujihara has resigned as chairman and CEO of Warner Bros. (Chris Pizzello/Chris Pizzello/Invision/AP)

Kevin Tsujihara, a powerful executive at a fast-changing WarnerMedia, will be leaving the company in the wake of allegations that he sought to find acting roles for a woman with whom he was having an affair.

Tsujihara, who has served as chairman and chief executive of Warner Bros. since 2013 and had been promoted just several weeks ago, said in a note to staff Monday that he would leave the company immediately.

“Over the past week and a half, I have been reflecting on how the attention on my past actions might impact the company’s future. After lengthy introspection, and discussions with [WarnerMedia chief] John Stankey over the past week, we have decided that it is in Warner Bros.’ best interest that I step down as Chairman and CEO," Tsujihara, 54, wrote in a letter to staff. “It has become clear that my continued leadership could be a distraction and an obstacle to the company’s continued success."

Tsujihara’s resignation marks a dramatic fall for a man who for many years occupied the rare ranks of the Hollywood anointed. Joining Time Warner 25 years ago in a business-development role at its theme parks, Tsujihara had risen quickly through its ranks with a reputation for digital savvy.

The resignation came after a report in the Hollywood Reporter this month revealed that Tsujihara had tried to find roles for Charlotte Kirk, an actress with whom he had a sexual relationship. Tsujihara involved other Warner Bros. executives and filmmakers in the effort, according to the publication. Kirk had small roles in two small WB films, “How To Be Single” and “Ocean’s 8.”

At the time of the report’s publication, Tsujihara’s personal attorney denied the allegations, saying that “Mr. Tsujihara had no direct role in the hiring of this actress.” Warner Bros. then launched an investigation into the executive’s actions. Tsujihara apologized to staff in a memo several days later.

“I deeply regret that I have made mistakes in my personal life that have caused pain and embarrassment to the people I love the most,” he wrote.

The Hollywood Reporter story came just days after a WarnerMedia reorganization had given Tsujihara more oversight at the company, and pressure mounted on Stankey to act. The company on Monday did not reveal details of the investigation but said that his actions made the move necessary.

“I want to let you know that following discussions over the past week, Kevin Tsujihara will step down from his role as Chairman and CEO of Warner Bros. It was a decision made with the best, long-term interests of the Company, our employees and our partners in mind,” Stankey wrote in a memo to staff. “Kevin has acknowledged that his mistakes are inconsistent with the company’s leadership expectations and could impact the company’s ability to execute going forward.”

The Hollywood Reporter had unearthed a number of text messages sent to Kirk by Tsujihara, billionaire James Packer and director Brett Ratner that it says show Tsujihara had enlisted powerful associates to help get Kirk roles in the wake of their affair.

Ratner’s attorney said his client was a friend of Kirk and simply was arranging to line up auditions for which she would then need to earn the roles. Kirk told THR that she “emphatically deni[es] any inappropriate behaviour on the part of Brett Ratner, James Packer, and Kevin Tsujihara, and I have no claims against any of them.”

The news casts the management future of WarnerMedia into question. The executive had been given an ever-larger portfolio, particularly in recent years. In 2005, he was named to head Warner Bros.' home-entertainment unit. Eight years later, he landed the top Warner Bros. job, succeeding outgoing chief Barry Meyer.

In a fierce internal competition, Tsujihara bested TV head Bruce Rosenblum and then film chief Jeff Robinov. His prize was the entire portfolio, as he took over the responsibilities previously held by both Rosenblum and Robinov, who soon after left the company.

Earlier this month, AT&T signaled its confidence in Tsujihara by giving him yet more responsibilities for other content divisions, including Cartoon Network, Adult Swim, Boomerang and Turner Classic Movies in addition to his existing roles heading WB’s film and TV studios.

Warner Bros. has been a powerful if not preeminent force on the movie front, last year releasing such films as “A Star is Born” and DC Comics’ hit “Aquaman.” Its TV division has also achieved success, with the long-running “The Big Bang Theory” set to wrap its run this spring and shows such as Fox’s “Lethal Weapon” and HBO’s “Westworld” continuing on the air.

But it is seeking to beef up under owner AT&T, which has sought to integrate divisions that were largely siloed under the company’s previous incarnation as Time Warner.

Tsujihara becomes the second major entertainment-company executive in recent months to resign after allegations of inappropriate behavior. In September, longtime CBS chief Leslie Moonves left the company after allegations of sexual misconduct.

WarnerMedia said it would announce an interim management structure in the coming days.

Correction: An earlier version of this story said ‘Lethal Weapon’ is aired by CBS. It’s aired by Fox.