Shortly after the president touches down in Riyadh aboard Air Force One, he will engage in a series of diplomatic meetings with King Salman and senior Saudi officials.
Trump's stop in an enthusiastic Saudi capital is the first in an eight-day, five-country swing across the Middle East and Europe.
Trump waved as he stood atop stairs that had been rolled to the side of the official presidential aircraft as it landed at Riyadh's airport.
Prime Minister Nawaz Sharif will leave for Saudi Arabia on Sunday to attend an global Islamic conference, where he may also meet US President Donald Trump.
Ahead of Mr Trump's arrival, billborads featuring his image and that of the Saudi king lined the highways of Riyadh.
Several jets then flew overhead leaving a red, white and blue trail.
To demonstrate their earnestness for an even closer alliance with Washington, the Saudis also are hosting a social media forum where Trump is to deliver a speech Sunday to the Muslim world.
In addition to King Salman and US President Donald J. Trump, 55 Heads of State and Government from the Muslim world have been invited to participate in the Summit. At a rally in Green Bay, Wis., in August, Trump said, "We have military bases that we rent - we pay rent to Saudi Arabia to protect them".More news: Anthony Weiner leaves court after guilty plea
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Trump will also visit Jerusalem and the Vatican on his tour.
Trump is also scheduled to meet with leaders of the six-nation Gulf Cooperation Council and have lunch with leaders of more than 50 Muslim countries.
Mr Trump's first overseas trip as president comes as he faces mounting controversy at home following the firing of FBI Director James Comey. However, when Saudi Arabia was asked whether although the first lady of the United States would have to dress appropriately, replied that Riyadh "usually does not require" a particular costume code, but "accepts the proposals".
But beneath the pageantry and symbolism remains the sting that billions of Muslims around the world felt after American voters elected Trump - a candidate who called for a "total and complete shutdown of Muslims" entering the United States, floated the idea of surveilling USA mosques and warned that Muslim refugees represented a national security threat.
Trump's spokesman Sean Spicer said the President edited the speech with his aides during the 14-hour journey from Washington. The massive arms deal is expected to include tanks, combat ships, missile defense systems, radar and communications and cybersecurity technology.
Quoting the Koran and calling attention to Islam's contributions to the world, President Barack Obama in 2009 addressed thousands of young students at Cairo University in Egypt in an attempt to turn the page on the policies of his predecessor that saw tens of thousands of USA troops deployed to Muslim countries. It notably refrains from mentioning democracy and human rights - topics Arab leaders often view as USA moralizing - in favor of the more limited goals of peace and stability.
A month after Donald Trump called for a "total and complete shutdown" of Muslims entering the USA, a hijab-wearing American named Rose Hamid stood up in the grandstands a few rows behind the presidential candidate.