After a more than three-year wait, US Army Pfc. Bradley Manning was sentenced to 35 years in prison on charges of espionage and theft.
He was also dishonorably discharged from the military.
The 25-year-old former junior intelligence analyst was convicted of 20 out of 22 counts against him in July for leaking US government information to WikiLeaks, the anti-secrecy website.
He could have faced a sentence as long as 90 years, although the prosecution had sought a 60-year term.
Defense attorney David Coombs suggested a more lenient sentence of 25 years, according to the Associated Press — as long as it would take for the classified information to expire.
He was expected to address the media in a news conference at 1:30 p.m. ET.
More from GlobalPost: Bradley Manning is sorry
In a pre-trial hearing, Manning said he was motivated to leak the hundreds of thousands of files to WikiLeaks in an effort to spark a discussion about US foreign policy and the military, the BBC reported.
Manning appeared apologetic last week as the sentencing portion of his trial in the military court came to an end.
"I'm sorry that my actions have hurt people and have hurt the United States," he said to military judge Col. Denise Lind, according to Agence France-Presse. "I want to go forward. I understand I must pay the price."
Manning is reported to be in a fragile emotional state and has been kept in seclusion in military custody since 2010 — a situation that has drawn the ire of his many international supporters who support the WikiLeaks mission.
After the verdict was read out, Manning's defense lawyer broke down, The Guardian's Paul Lewis tweeted.
Wednesday's verdict will likely be watched with great interest by another famous whistleblower: Edward Snowden, a former intelligence National Security Agency contractor hiding in Russia after releasing details of US surveillance programs.
Manning's supporters also on Wednesday launched a "Pardon Bradley Manning" campaign, hoping to secure 100,000 signatures by Sept. 20.
Along with Amnesty International, the Bradley Manning Support Network established the petition at White House website.