Meanwhile, Wikileaks released over 60,000 emails from US private intelligence firm HBGary to celebrate Brown's release.
He pleaded guilty to threatening an FBI agent in an online video and providing a link to data which had been stolen from the private intelligence group Stratfor, which was hacked by Anonymous in 2011.
Barrett Brown was supported personally by Wikileaks founder Julian Assange.
"Nothing so well describes the surreal universe that has enveloped the United States as yesterday’s sentencing hearing of Barrett Brown," Assange wrote on the Wikileaks website responding to the Brown's sentence. "Barrett has been jailed without trial for over two years now. He faces eight and a half more years. His next sentencing hearing is due in January 2016. The situation also involves me personally and the work of WikiLeaks,” Assange wrote on the Wikileaks website.
"These charges are at odds with national and international protections for the press and freedom of expression. The third charge concerns his speech acts after the FBI threatened to charge his mother unless he handed over his source material. There are no other charges," Assange wrote.
Assange was sure the situation with Brown is "a direct result of his journalistic work."
"The most serious claim against Barrett Brown is that six months after the March 6, 2012, FBI raid on his mother’s address he tweeted 'illegally shoot the son of a [word expelled].' It sounds bad. It is a clear incitement to murder. The FBI claim that the 'son of a [word expelled]' Barrett was referring to was one of their agents. That is false. The 'son of a [word expelled]' is me," Assange said with a view to Fox News host Bob Beckel.
In December 2010, Beckel called for Assange's assassination by US special forces.
Barrett Brown was the mastermind behind the so-called Project PM, a crowdsourced investigation focused on research and analysis of leaked documents.