Mohammed Al-Zahrani, regarded as a previously active member of Al-Qaeda, is the latest of seven prisoners freed from the controversial jail in Cuba in the past three weeks, and his release comes just days after authorities transferred five inmates to Georgia and Slovakia.
The 45-year-old, once considered to present a "high risk" to American interests, was transferred from the prison on a specially chartered flight Friday.
Zahrani was approved for removal last month by a special review board created by Obama in his efforts to shut the prison, a Pentagon statement said, adding that Congress was duly informed of the transfer.
As part of the deal to release him, Zahrani will take part in a rehabilitation and counseling program in Saudi Arabia.
The review board, composed of representatives from six government agencies, including the State and Defense departments, decided on October 3 that Zahrani no longer represented a threat to the United States.
Ian Moss, spokesman for Cliff Sloan, the State Department envoy who negotiates transfer deals, praised the Saudi rulers and the "close partnership" between Washington and Riyadh.
"Our two governments will continue to work together to take appropriate steps to mitigate any potential threats that may be posed by Guantanamo detainees transferred to Saudi Arabia," Moss told AFP.
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Of the 142 inmates remaining, a total of 73 have been cleared for release -- some of them during the administration of Obama's predecessor, George W. Bush -- but remain incarcerated without charges or trial.
Obama has accelerated releases in recent weeks, including sending home the first Yemenis since 2010.
"A total of 13 detainees have been transferred this year," noted Paul Lewis, Special Envoy for Guantanamo Detention Closure, in Saturday's statement.
"This strikes a responsible balance and reflects the careful deliberation the Secretary of Defense brings to the transfer process, and follows a rigorous process in the interagency to review several items including security review prior to any transfer," he added.
In early November, a military official told AFP that about 15 detainees would be transferred over the winter. Six inmates are expected to go to Uruguay, and another four could be sent back to Afghanistan.
The closure of the Guantanamo prison, set up to hold detainees from President George W. Bush's post-9/11 "War on Terror," was a prominent part of Obama's election campaign in 2008.
Yet attempts to realize his ambition have been thwarted by domestic and international obstacles, leaving the fate of the jail and its prisoners in limbo.
Pentagon spokesman Lieutenant Colonel Myles Caggins told AFP after Zahrani's release that "we are continually moving responsibly towards the goal of closing Guantanamo with security as a primary concern."