ABC News is set to pay $15 million to settle a defamation lawsuit brought by Donald J. Trump.

The agreement was a significant concession by a major news organization and a rare victory for a media-bashing politician whose previous litigation efforts against news outlets have often ended in defeat.

Under the terms of a settlement revealed on Saturday, ABC News will donate the $15 million to Mr. Trump’s future presidential foundation and museum. The network and its star anchor, George Stephanopoulos, also published a statement saying they “regret” remarks made about Mr. Trump during a televised interview in March.

ABC News, which is owned by the Walt Disney Company, will pay Mr. Trump an additional $1 million for his legal fees.

The outcome is an unusual win for Mr. Trump, who has frequently sued news organizations for defamation and frequently lost, including in litigation against CNN, The New York Times and The Washington Post.

Several experts in media law said they believed that ABC News could have continued to fight, given the high threshold required by the courts for a public figure like Mr. Trump to prove defamation. A plaintiff must not only show that a news outlet published false information, but that it did so knowing that the information was false or with substantial doubts about its accuracy.

“We are pleased that the parties have reached an agreement to dismiss the lawsuit on the terms in the court filing,” an ABC News spokeswoman said on Saturday. A lawyer for Mr. Trump declined to comment on the agreement. A spokesman for his presidential transition did not respond to an inquiry.