The release of the documents has been described as the most extensive leak of classified information in U.S. history.
His sentence is less than his defense team recommended (25 years) but far less than the 60 years prosecutors asked, or for the 90 years he could have received based on his crimes.
The former Army intelligence analyst will also be reduced in rank from private first class to private, receive a dishonorable discharge and forfeit all pay and allowances.
He was escorted out of the courtroom, stone-faced, after a military judge announced the sentence. He will serve his sentence at the military's detention facility at Fort Leavenworth, Kan.
Manning, 25, will be eligible for parole after serving a third of his sentence. He will receive his parole review after little more than 8 years, as he has a 1,294-day credit toward his sentence.
Those days amount to 1,182 days Manning served in pre-trial confinement, plus 112 more he received for rough treatment at the Marine brig in Quantico, Va.
Manning was found guilty of 20 of the 22 charges he faced for espionage, theft and fraud. He was not found guilty for the most serious charge -- aiding the enemy -- which carries a life sentence.
Nevertheless, the sentence is the longest ever handed down in a case involving a leak of U.S. government information solely for the purpose of making the information available to the public.