Sami al-Hajj had been in US custody for more than six years. He was detained in Afghanistan in 2001. He arrived in the Sudanese capital Khartoum on a US military plane in the early hours of Friday morning.
After a 16-month hunger strike, Mr Hajj grimaced as he was carried off the plane by US military personnel.
"I have been so overwhelmed with happiness that I've been in tears," he said shortly after his arrival.
"I have every right to cry after I've survived these seven horrid years of humiliation, repression and injustice for no fault on my part apart from being a Muslim."
Al-Jazeera showed footage of Mr Hajj being carried into the hospital on a stretcher, looking frail but smiling and surrounded by well-wishers.
"We are concerned about the way the Americans dealt with Sami, and we are concerned about the way they could deal with others as well," said Wadah Khanfar, managing director of al-Jazeera's Arabic service.
"His detention for six years, without the most basic due process, is a grave injustice and represents a threat to all journalists working in conflict areas," said Joel Simon, executive director of the New York-based Committee to Protect Journalists.
Mr Hajj was working as a cameraman for al-Jazeera when he was arrested by Pakistani troops near the Afghan border in December 2001 and later handed over to the US military.http://news.bbc.co.uk/2/hi/americas/7378828.stm
I'm outraged. I'm outraged that my country would treat someone this way in violation of international law. I'm outraged that America would hold a journalist for more than six years without evidence. I'm outraged that an innocent man was tortured and abused.
But as much as all of these, I'm outraged that this story will only be noticed by the rest of the world. The American media will ignore the story of a fellow journalist unjustly incarcerated in favor of the latest celebrity scandal or political horse race sound byte. And they wonder why we're losing respect internationally.
Our current president has brought shame and disgrace upon our nation. For this crime, and countless others, he should stand before an international tribunal and face the consequences determined. I know that will only happen after Satan takes up driving a Zamboni, but it would be the only way to restore America's honor.