The lawsuit, filed Oct. 22 in Los Angeles Superior Court, alleged defamation and invasion of privacy. Duchovny, 48, was seeking $1 million in damages.
A one-page notice of dismissal of the case was filed Thursday by Duchovny's lawyer, Stanton L. Stein, who was not immediately available for comment on why his client was no longer pursuing the case. The complaint was dropped "with prejudice," meaning it cannot be brought back again.
Duchovny, best known as FBI agent Fox Mulder on the "X-Files," and 42-year-old "Bad Boys" star Leoni married in 1997 and have two children. However, they are currently separated.
In his lawsuit, Duchovny accused the Daily Mail of posting a story online last month that said he cheated on Leoni with a tennis instructor named Edit Pakay.
The Daily Mail story was removed from the paper's Web site a few days later. But other news outlets picked up the article and placed versions on their Web sites, which caused additional stress to Duchovny, the lawsuit stated. The lawsuit also said Duchovny never hired Pakay to be his tennis coach. Pakay says she is a friend of Duchovny's and they played tennis a few times, according to the lawsuit.
Duchovny portrays a philandering writer on the Showtime cable television series "Californication." His films include 1993's "Kalifornia," in which he co-starred with Brad Pitt.
Duchovny was recently treated for sex addiction.