Steve Wynn, the former chief executive of Wynn Resorts Ltd. , filed a defamation lawsuit this week against a former Wynn Resorts employee, alleging that he smeared Mr. Wynn by spreading false accusations of alleged sexual misconduct in media reports.

Jorgen Nielsen, a former artistic director of the Wynn Las Vegas salon, was quoted by name in two articles about Mr. Wynn and the casino company in The Wall Street Journal earlier this year. The articles detailed allegations from people who have worked at Wynn Resorts that would amount to a decadeslong pattern of sexual misconduct by Mr. Wynn, and managers’ practice of ignoring or dismissing their complaints.

Mr. Wynn resigned in February as chairman and CEO of Wynn Resorts after the Journal published the first article, in January. He said at the time of his resignation that he couldn’t be effective in an environment in which “a rush to judgment takes precedence over everything else, including the facts.” In a statement for the first Journal article, which reported Mr. Wynn had paid $7.5 million in 2005 to a manicurist who told others he forced her to have sex, Mr. Wynn said the idea that he ever assaulted a woman was “preposterous.”

The lawsuit alleges the Journal’s reporting set off an “open season” on Mr. Wynn, “where truth and context were ignored, and his guilt was presumed based only on unproven accusations.”

Mr. Nielsen said he was unaware of the lawsuit and declined to comment further.