Mr. Thiel weighed in on the controversy Saturday night, saying through a spokesman that he did not support a religious test for entry into America, "and the administration has not imposed one." He was the only major figure in Silicon Valley to vocally support the president.
Six years ago, however, Mr. Thiel didn't always consider America First, as Mr. Trump's slogan goes. According to the application, Mr. Thiel saw the vast promise of New Zealand and set up a fund there to invest in its start-ups. He vowed to become an unofficial ambassador for the country if granted citizenship.
"I intend to devote a significant amount of my time and resources to the people and businesses of New Zealand," he told the authorities.
At one point he had invested $3 million in Xero, a New Zealand accounting firm, according to the company, and $4 million in Pacific Fibre, which hoped to build a trans-Pacific cable, according to local news reports.
He said that "the wide global network I have cultivated would be of great value to New Zealand, and it would give me great pride to let it be known that I am a New Zealand citizen and an enthusiastic supporter of the country."
About 30,000 people apply for citizenship every year in New Zealand, where the population is less than five million, according to data from the country's Internal Affairs Department. Only a handful — around one to two dozen a year — are approved for citizenship by the minister of internal affairs under "exceptional" circumstances, the data showed.
Mr. Thiel was one of those. In the application, he noted that he did not fulfill the residency requirements and said that he did not intend to live in the country if he secured citizenship.
Iain Lees-Galloway, a spokesman for Labour, the country's main opposition party, said the citizenship file confirmed "everything that we suspected."
"The decision to grant Mr. Thiel citizenship is entirely based on money," Mr. Lees-Galloway said in an interview.
As the application process continued, Mr. Thiel was not shy about mentioning that fact.
"I had a sudden thought last night that I may have overlooked mentioning Peter Thiel's $1 million donation to the Christchurch earthquake appeal," an email in the file read, referring to a gift in New Zealand dollars. While the sender and recipient were redacted, it was apparently sent by a member of Mr. Thiel's staff. Nearly 200 people were killed in the quake, which struck in February 2011.
"Essentially, Mr. Thiel has been granted citizenship on the grounds that he is a wealthy person," Mr. Lees-Galloway said.
Mr. Thiel received his citizenship in a ceremony at the New Zealand Consulate in Santa Monica, Calif., the documents showed.
"He didn't even become a citizen in New Zealand — that demonstrates to me that he has no ongoing commitment to New Zealand, and I don't think he is a good candidate for New Zealand citizenship," Mr. Lees-Galloway said. "It's getting close to corruption."
Mr. Lees-Galloway said the New Zealand Citizenship Act of 1977 was out of date. "We live in a turbulent world, an unstable world where New Zealand citizenship has actually become an asset and our government seems to be treating it like a commodity," he said. "We need to decide as a nation on what grounds do we grant citizenship."
A spokesman for Mr. Thiel in San Francisco declined to comment Tuesday night. The New Zealand Interior Ministry declined to comment further on the filings.
Mr. Thiel gave more than $1 million to Mr. Trump late in the campaign. The donation received much criticism in Silicon Valley, but it got Mr. Thiel a major position on Mr. Trump's transition team.
Nathan Guy, the minister of internal affairs at the time that Mr. Thiel was granted citizenship, defended the move this week. "The decision that I made in my view was the right one," Mr. Guy told the local news media. "I felt with his good character and the contribution that he was going to make to New Zealand, and indeed has made, that he's suitable and worthy of being a fantastic New Zealand citizen."
Mr. Thiel received the right of permanent residency in 2007, which gave him the ability to come and go freely. But citizenship was the goal.
His advisers wrote to the government that Mr. Thiel believed "citizenship is irrevocable."
"It is the public recognition of a hallowed bond," they said. "For that reason and others, he is prepared to make this solemn allegiance and to hereby embrace and contribute to the life, history and culture of New Zealand."