Wealth funds in the United Arab Emirates and Qatar have invested hundreds of millions of dollars with Jared Kushner’s private equity firm, according to people with knowledge of the transactions, joining Saudi Arabia in backing the venture launched by former President Donald J. Trump’s son-in-law as he left the White House.

The infusion of money from interests in the two rival Persian Gulf monarchies reflects the continued efforts by Mr. Trump and his aides and allies to profit from the close ties they built to the Arab world during his presidency and the desire of leaders in the region to remain on good terms with Mr. Kushner as his father-in-law seeks the presidency again.

The Emiratis invested more than $200 million with Mr. Kushner’s firm, Affinity Partners, two people told about the transactions said. The U.A.E.’s embassy in Washington declined to comment. A Qatari entity invested a similar sum, according to two people with knowledge of that deal. A spokesman for the Qatari embassy in Washington declined to comment.

The investment from the U.A.E. came through a sovereign wealth fund, but the identity of the Qatari investor is unclear. An Affinity Partners official did not respond to an email seeking comment.

Top Emirati officials have a close relationship with Mr. Kushner, forged during the Trump administration. And the Kushner family has previously benefited from Qatari funds. A Qatar-linked company helped bail out the Kushners’ debt-ridden tower in midtown Manhattan, 666 Fifth Avenue, during the Trump presidency.

But despite these relationships, Emirati and Qatari officials were at first reluctant to invest in Mr. Kushner’s private equity fund, at least in part because of the political risks involved, according to people familiar with both governments’ internal deliberations. The Times previously reported that Qatari officials feared they would face unfavorable treatment if they turned down Mr. Kushner’s invitation to invest and Mr. Trump returned to power.

It is not unusual for insiders from both parties to benefit financially from deals abroad after leaving government service, particularly in the Middle East. There is a long history of firms populated by former officials from Democratic administrations signing lucrative contracts with Gulf nations, and there are few laws or ethics guidelines prohibiting it.

But the scale of the investments Mr. Kushner’s venture has received from the Gulf countries — in the range of $2.5 billion — and the timing, coming relatively soon after his leaving the White House, are striking and have drawn criticism from Democrats and ethics experts.

The newly disclosed investments are not especially large coming from energy-rich nations whose sovereign wealth funds manage hundreds of billions of dollars in assets. And they are far smaller than the commitment made earlier by the main Saudi sovereign wealth fund, a $650 billion entity known as the Public Investment Fund, which, as The New York Times has reported, invested $2 billion with Mr. Kushner in 2021. Affinity Partners has confirmed that the Public Investment Fund was backing it without giving details on the amount.

Both the U.A.E. and Qatar have a history of hedging their bets on U.S. politics. The investments appear to be the latest indication that they want to maintain warm relations with prominent officials from the Trump administration — especially if Mr. Trump were to become president again — even as they work with the Biden administration.

But the investments reflect not just an eye toward the future in the U.S., but also an acknowledgment of their relationship with Mr. Kushner, who left the White House with an expansive network of contacts, and with whom they worked closely.

Affinity Partners makes only limited public disclosures, but the branch of the firm that handles money from Mr. Kushner’s overseas backers held $2.5 billion in capital on behalf of three different foreign investors, according to a financial filing dated last March. Updated disclosures, which are expected to be filed by Friday, are likely to show that Affinity Partners now manages roughly $3 billion, according to a person familiar with the matter.

As a top White House adviser to Mr. Trump while he was in office, Mr. Kushner was an active participant in American diplomacy in the Middle East and helped orchestrate a regional pact, the Abraham Accords, that normalized relations between Israel and several Arab countries, including the United Arab Emirates, in 2020.

During the final days of the Trump presidency, he played a role in discussions that helped lift an economic and diplomatic blockade of Qatar by its neighbors. The blockade, led by Saudi Arabia, had been imposed in 2017 at a time when Mr. Kushner was cultivating a relationship with Saudi Prince Mohammed bin Salman — who was about to become next in line to the throne in the kingdom.

John R. Bolton, who served as Mr. Trump’s national security adviser, said he never heard Mr. Kushner directly address the opportunities that his contacts in the Middle East could bring him after leaving government.

“But certainly the way in which he’s approached it upon leaving the White House has been very systematic and very effective,” Mr. Bolton said.

Mr. Kushner is not the only former Trump administration official to benefit from connections in the Middle East since Mr. Trump’s term ended. Steven T. Mnuchin, the former Treasury secretary, also runs an investment firm with backing from sovereign wealth funds in the Gulf. On Thursday, both he and Mr. Kushner appeared at an investment conference in Miami Beach sponsored by a nonprofit led by the governor of Saudi Arabia’s Public Investment Fund, Yasir al-Rumayyan.

Since leaving office, Mr. Trump, like his son-in-law, has chased Middle East deals. He announced one with a Saudi real estate company, which intends to build a Trump-branded hotel, villas and a golf course as part of a $4 billion real estate project in Oman that is backed by Oman’s government. And he is promoting the Saudi-backed LIV Golf tour at his golf courses.

But in Mr. Kushner’s case, investors in the region had raised questions about his lack of investment experience, and Democrats have criticized the speed with which he secured financial commitments from countries he had only recently been dealing with in an official capacity. Mr. Kushner locked in the $2 billion investment from the Saudis only months after he left the White House.

Last year, Representative Carolyn B. Maloney of New York, who at the time was chair of the House Committee on Oversight and Reform, opened an investigation into whether Mr. Kushner traded on his government position to secure the Saudi investment.

“Your close relationship with Crown Prince bin Salman, your pro-Saudi positions during the Trump administration, and PIF’s decision to fund the lion’s share of your new business venture — only six months after the end of your White House tenure,” Ms. Maloney wrote in a letter to Mr. Kushner, “create the appearance of a quid pro quo for your foreign policy work.”

A spokesman for Mr. Kushner replied at the time that “Mr. Kushner fully abided by all legal and ethical guidelines both during and after his government service.” Republicans closed the investigation into Mr. Kushner when they took control of the House this year.

Mr. Kushner and Mr. Mnuchin spent some of the final days of the Trump presidency in the Middle East. Mr. Kushner was focused on expanding the Abraham Accords, and both men were pushing a new initiative called the “Abraham Fund” — a U.S. government program they said would raise billions of dollars for Middle East projects but which never got off the ground and ended after Mr. Trump left office.

Shortly after leaving government, both Mr. Kushner and Mr. Mnuchin established their respective private equity firms, and they soon began courting some of the very same governments that had been their official counterparts just weeks before. Both recruited into their firms members of the Trump administration who had strong relationships with the Gulf countries they were now pursuing for investments.

Mr. Kushner brought on as a partner his former White House colleague Avi Berkowitz, a young aide who was later elevated to play a key role in Middle East negotiations. Among other former Trump officials with trade and diplomatic experience, Mr. Kushner also hired retired Army Maj. Gen. Miguel Correa — a former defense attaché at the U.S. embassy in Abu Dhabi — whose strong high-level relationships with the Emiratis helped cement the Abraham Accords.

By June 2021, the Saudi Public Investment Fund was considering backing Mr. Kushner’s Affinity Partners with $2 billion in what Mr. al-Rumayyan described as a “strategic” investment, even as a fund investment advisory panel recommended against providing capital because of Mr. Kushner’s lack of an investment track record and the public relations risks involved, according to internal documents disclosed last year by The Times.

Ultimately, the Public Investment Fund’s full board, whose chairman is Prince Mohammed, Saudi Arabia’s de facto ruler, voted to reject the advisers’ warnings and approved the Affinity Partners investment.

The Saudi arrangement alone stands to earn Mr. Kushner and his partners more than $20 million a year in fees, regardless of the performance of their investments.

The Saudi Public Investment Fund also put $1 billion into Mr. Mnuchin’s fund, Liberty Strategic Capital, though on less generous terms than it had agreed to with Affinity Partners, the documents reviewed by The Times show.

Mr. Kushner’s role as a Gulf power player was evident in February, at the wedding in Abu Dhabi of Mr. Berkowitz, his colleague at Affinity and in the White House.

Among those who attended the event under glass chandeliers in the sweeping royal ballroom of the St. Regis hotel on Saadiyat Island: Sheikh Tahnoon bin Zayed Al Nahyan, a brother of the United Arab Emirates’ leader, Mohammed bin Zayed Al Nahyan. Sheikh Tahnoon, who is also the national security adviser and oversees major Emirati investments, sat for a time next to Mr. Berkowitz at the head table, according to two attendees.

The Republican donor Miriam Adelson; Yousef al-Otaiba, the Emirati ambassador to the United States; and Richard Attias, a close adviser to Mr. al-Rumayyan of the Saudi Public Investment Fund, were also at the reception, where an attendee said guests dined on lamb chops and kosher chocolate mousse and danced to Israeli and American music.

Even the ceremony that preceded it made a statement about regional diplomacy: It was held at a synagogue in the Abrahamic Family House, a newly established interfaith center in Abu Dhabi not far from the hotel.

Mr. Kushner’s Qatari connections were on public display in December, when he was spotted, alongside the Tesla founder Elon Musk, in a V.I.P. suite at the World Cup final match in Doha.

Mr. Kushner has told several people he does not want to be part of another presidential campaign. Yet he has maintained some public proximity to Mr. Trump’s latest run for the presidency. In November, he took a conspicuous seat in the front row at Mr. Trump’s campaign kickoff event at the former president’s private club, Mar-a-Lago.