U.S. District Judge George Daniels in Manhattan said the plaintiffs' allegations "narrowly articulate a reasonable basis" for him to assert jurisdiction under a federal law, the Justice Against Sponsors of Terrorism Act.
Saudi Arabia had long had broad immunity from Sept. 11 lawsuits in the United States, before the U.S. Congress in September 2016 overrode a veto by President Barack Obama to allow such cases to proceed.
Lawyers for Saudi Arabia did not immediately respond to requests for comment.
The Saudi government has long denied involvement in the attacks, in which hijacked airplanes crashed into New York's World Trade Center, the Pentagon outside Washington, D.C., and a Pennsylvania field. Nearly 3,000 people died.
Daniels has overseen litigation against Saudi Arabia by the families of those killed, roughly 25,000 people who suffered injuries, and a variety of businesses and insurers.
"We're delighted that Judge Daniels denied Saudi Arabia's motion to dismiss," James Kreindler, a lawyer for many of the plaintiffs, said in a phone interview.
In two decisions, Daniels also dismissed claims by various plaintiffs against several other defendants, saying he lacked jurisdiction.
Among these defendants were two Saudi banks, National Commercial Bank and Al Rajhi Bank, and Saudi Binladin Group, a construction company controlled by the bin Laden family.
They were accused of knowingly providing material support to Osama bin Laden or al Qaeda, in the form of funds and financial services, to carry out the attacks.
(Reporting by Jonathan Stempel in New York; Editing by Tom Brown)
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
Follow NDTV for latest election news and live coverage of assembly elections 2019 in Maharashtra and Haryana.
Subscribe to our YouTube channel, like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.