The Pentagon says that Jawad was 16 or 17 when he was apprehended on suspicion of a grenade attack that killed two US soldiers and their interpreter.
Jawad's release comes just over three weeks after a US federal judge said that the US government must release him by August 24.
A military judge had dismissed most of the evidence against Jawad at the end of 2008, while a federal prosecutor left the case, saying that Jawad had been tortured before he made his statements.
Major David Frakt, the US military lawyer who had defended Jawad before the military tribunal created under the Bush administration, said the right decision had been made.
"Mr Jawad has finally returned home to celebrate Ramadan with his family after nearly seven long years away. This is a tremendous victory for justice and the rule of law," Frakt said.
"Although nothing can ever replace those lost years, fortunately this remarkable young man is still young enough to build a life for himself.
"He is eager to go back to school and complete his education so that he can help others in Afghan society."
Fourteen of the remaining 228 prisoners at Guantanamo are set to be released soon after US federal courts said they were not guilty of any crime.
Scores more detainees could also be released by President Barack Obama's administration, which is reviewing all detainees' cases.
Most of the detainees that are set to be released are waiting for a third country to accept them. The Washington Post last week cited Obama administration officials as saying that nine European countries are considering whether to take former detainees.