Al-Moayad received a hero's welcome from ministers, political leaders, other dignitaries and thousands of people on his arrival in Yemen on Tuesday.
The man was sentenced to 75 years in prison by a US court in 2005 for providing financial support to al-Qaeda and Hamas, after being extradited from Germany where he was arrested two years earlier.
But a US appeals court ordered a retrial last October after overturning the convictions on grounds they were prejudiced by inflammatory testimony from unrelated terrorism cases in the original trial.
He was released after his lawyer struck a plea bargain deal with US prosecutors, sources close to his family said.
Under the agreement, he pleaded guilty to providing aid to Hamas, which is listed among terrorist groups by US government, and was sentenced to six
years time served.