SAN FRANCISCO — Peter Thiel, true to his reputation as the most contrarian soul in Silicon Valley, is doubling down on Donald J. Trump.

The only prominent supporter of the Republican candidate in the high-tech community, Mr. Thiel is making his first donation in support of Mr. Trump’s election. He will give $1.25 million through a combination of super PAC donations and funds given directly to the campaign, a person close to the investor said on Saturday.

The donation puts the billionaire investor high on a very short list of big Trump contributors. One of the biggest donors is Robert Mercer of the hedge fund Renaissance Technologies. He and his daughter Rebekah Mercer have given $15.5 million in support of the Republican candidate’s election, according to the Center for Responsive Politics. Geoffrey Palmer, a Los Angeles developer, has donated $2 million.

Mr. Thiel, who spoke at the Republican National Convention, apparently is unfazed by the storm around the candidate in the last week following the broadcasting of lewd conversations recorded by the syndicated program “Access Hollywood.” The source, who requested anonymity, said the investor feels the country needs fixing, and Mr. Trump can do it.