Trump posted the news on his Truth Social media platform after meeting with Marcos in the Oval Office, where he had signalled a deal could be reached during the visit.
"It was a beautiful visit, and we concluded our Trade Deal, whereby The Philippines is going OPEN MARKET with the United States, and ZERO Tariffs. The Philippines will pay a 19% Tariff," Trump said, calling Marcos a "very good and tough negotiator".
Trump said the two Pacific allies would also work together militarily but gave no details.
Marcos told reporters at the start of the meeting that the United States was his country's "strongest, closest, most reliable ally".
The 19 per cent tariff rate was just below the 20 per cent threatened by Trump earlier this month but above the 17 per cent rate set in April when Trump announced what he called reciprocal tariff rates for dozens of countries.
It matches the 19 per cent rate announced for Indonesia and bests Vietnam's slightly higher rate of 20 per cent.
The United States had a deficit of nearly $US5 billion ($A7.7 billion) with the Philippines last year on bilateral goods trade of $US23.5 billion.
Trump said the two countries did "a lot of business" with each other, adding the "very big numbers" in the trade agreement would only grow larger.
During the Oval Office event, Trump said he may visit China for a landmark trip "in the not-too-distant future" and noted the Philippines had distanced itself from China after his election last November.
"The country was maybe tilting toward China but we un-tilted it very, very quickly," Trump said.
Critics warn Trump's tariffs on nearly all foreign goods could boost prices for US consumers, complicating his push for the Federal Reserve to lower interest rates.
No comment was immediately available from Marcos, who did not speak to reporters before leaving the White House grounds.
Philippine Assistant Foreign Secretary Raquel Solano said last week trade officials have been working with US counterparts seeking to seal a "mutually acceptable and mutually beneficial" deal.
Marcos, who arrived in Washington DC on Sunday, met with Defense Secretary Pete Hegseth and Secretary of State Marco Rubio on Monday.
During his trip, he will also meet US business leaders investing in the Philippines.
