The dead include four Saudis, two people from Bangladesh and one person each from the US, Jordan, Palestine, Syria, Sudan and Egypt, the Saudi civil aviation authority said. At the latest count, officials said, 309 were wounded.
Hospitals were flooded with wounded brought by ambulance and helicopter, people briefed on the matter said. Some were in critical condition.
Flight-tracking site flightradar24 showed all flights to Riyadh had either been diverted or cancelled, with only a helicopter hovering over the airport at one point.
Saturday's attack, the deadliest in the kingdom in more than a decade, occurred without warning, with no alert issued by Saudi Arabia's threat warning system.
This week's two previous attacks on King Khalid International Airport left four people dead and caused heavy damage to a Saudi commercial plane parked on the tarmac.
The deadly strikes exposed vulnerabilities in the kingdom's defence capabilities as it wages an air campaign against the Houthis to support a ground war by the Yemeni government against the Iran-backed group.
Saudi Arabia and the Yemeni government have claimed hundreds of strikes on targets in Houthi-held territory. The Houthis have said these killed civilians including women and children.
All flights were diverted from Riyadh on Saturday, and operations at the airport that serves a city of roughly eight million people were temporarily suspended, the Saudi civil aviation authority said.
The head of the Houthi media office said in a post on X after the attack that the group had "shut down Riyadh international airport".
The Houthis have said airliners should avoid Saudi airspace, declaring it a zone of military operations after the Saudi-backed Yemeni government launched an offensive against the group on Monday.
US President Donald Trump, speaking to reporters outside the White House, was asked whether Washington planned to join Saudi strikes on the Houthis.
"We may. We're going to look at it. We just found out about the recent attack, so we'll make a decision. We move very quickly," he said.
US Secretary of State Marco Rubio condemned the attacks, saying they "demonstrate a blatant disregard for innocent civilian life".
One eyewitness at the airport on Saturday reported seeing an explosion and then multiple people lying injured on the ground inside. More than a dozen ambulances were seen rushing towards the facility. A video verified by Reuters showed ambulances at the airport.
An injured traveller told Reuters they saw something fly across the sky outside the airport before part of the ceiling near a departure gate collapsed.
The US embassy in Riyadh said it was "aware of attacks" and "strongly recommends all US citizens avoid this airport and surrounding areas".
Saudi Arabia entered the Yemen war in 2015 at the head of an Arab coalition to try to force the Houthis out of the Yemeni capital Sanaa. The Houthis had stormed Sanaa the previous year, pushing out government forces.
The war was fought to a bloody stalemate, with hundreds of thousands of Yemenis killed by fighting and famine. Saudi Arabia struck a 2022 deal with the Houthis, freezing the conflict.
That ceasefire unravelled over the summer, culminating in a lightning Houthi advance that took the Red Sea chokepoint of Bab el-Mandeb from Saudi-backed government forces.
The Saudi-backed Yemeni government began an offensive this week to try to retake that territory, which has so far made slow gains, even as the Houthis put the country's third-largest city, Taiz, under siege.
Houthi attacks on Thursday and earlier in the week had already prompted a number of carriers to suspend or cancel services to the Saudi capital, shortly before Riyadh is due to host major energy and investment conferences.
Organisers of those conferences said ahead of the strikes on Saturday they would go ahead as planned.
with dpa
