'Relationship of respect'
He told the court on Thursday he was stunned to learn bin Laden was behind the bombing of the warship USS Cole in 2000, but went back to work for him because he could not find another job that paid enough to support his family.
"I couldn't beg," Hamdan told the Guantanamo court. "I had to work."
"It's true there are work opportunities in Yemen, but not at the level I needed after I got married and not to the level of ambitions that I had in my future," he said, reading in Arabic from a prepared statement.
He said he merely had a "relationship of respect" with bin Laden, as would any other employee.
Hamdam has been held at the detention centre for more than six years and faced 10 specific charges.
During the trial he said he denied the allegations against him, saying he worked for bin Laden only as a driver and had no knowledge of al-Qaeda attacks.
|Hundreds of prisoners remain in Guantanamo Bay prison [EPA]
The Bush administration has faced heated criticism over the Guantanamo Bay prison camp and the special tribunals, which operate under different rules to other military or civilian courts .
Hamdan was detained at a roadblock in southern Afghanistan in November 2001, allegedly with two surface-to-air missiles in his car.
It was the Bush administration's third attempt to try Hamdan, who won a US supreme court victory in 2006 that meant the first version of the Guantanamo court system was scrapped.
The charges against him were twice dropped and refiled.
His defence lawyers say he was subjected to abuse while in US custody, including humiliating interrogation tactics and sleep deprivation.