Abdel Malik Wahab al Rahabi was held in the controversial US-run Guantanamo Bay prison for more than 14 years without trial or charges.
The US transferred a Yemeni Guantanamo Bay prison detainee to Montenegro on Wednesday, bringing down the controversial prison's population to 79.
Abdel Malik Wahab al Rahabi, 37, was among the 20 initial detainees who were brought to the prison in January 2002 in the aftermath of the 9/11 attacks. He was never charged with any crime or put on trial by a court in more than 14 years.
He was among the people in the infamous Guantanamo photo that shows prisoners on their knees in a cage with their faces covered.
According to Pentagon documents, Al Rahabi had been accused of being a bodyguard for the late al Qaeda leader Osama bin Laden in Afghanistan.
In December 2014, Guantanamo Bay's interagency review panel, dubbed the Periodic Review Board, found that al Rahabi was no longer a significant security threat to the United States and recommended his transfer. However, it recommended al Rahabi to be sent to a third-country instead of his home country Yemen because it is too unstable to accept prisoners from Guantanamo.
Al Rahabi is married and has a daughter whom he last saw when she was three months old. During a review panel, he said he feels "saddened for each passing day of my life living far away from her."
The Montenegrin government in a statement said they received al Rahabi as part of humanitarian programme overseen by the US government.
The statement said the transferred prisoners "will eventually be free to choose the country they want to live in."
During his presidential campaign and throughout his term in office, US President Barack Obama vowed several times to close Guantanamo Bay.
The administration has increased efforts towards that aim, transferring Guantanamo detainees to their home countries or to third countries, but the process has been stalled by the Republican controlled US Congress.
The Congress bans the use of funds to transfer Guantanamo detainees to the US for any purpose, such as detention in prisons in the US and trial in federal courts.
The only ways that the cases of detainees are being reviewed are through military courts and periodic review boards.
With only months left until the end of Obama's tenure, it would take years to process all of the detainee cases due to the slow pace of current review mechanisms, making it unlikely for Obama to fulfill his promise.