US District Judge Reggie Walton also imposed on Libby a fine of $250,000 and two years probation after his release from prison.
"People who occupy these types of positions, where they have the welfare and security of nation in their hands, have a special obligation to not do anything that might create a problem," Walton said.
"It is respectfully my hope that the court will consider, along with the jury verdict, my whole life," Libby said in brief remarks to the judge.
Libby's lawyers were expected to ask Walton to suspend the sentence while they appeal the case.
Cheney described the jailing of his former aide and friend as a "tragedy".
|"The president has not intervened so far in any other criminal matter and he is going to decline to do so now" |
White House spokeswoman
"The defence has indicated it plans to appeal the conviction in the case. Speaking as friends, we hope that our system will return a final result consistent with what we know of this fine man," he said.
The White House, meanwhile, has said that George Bush will not intervene in the case while the appeals process is under way.
"The president has not intervened so far in any other criminal matter and he is going to decline to do so now," Dana Perino, White House spokeswoman, said.
"The president said that he felt terrible for the family, especially his wife and his kids," she added.
Libby was found guilty of lying about conversations he had about Plame, but not of actually leaking her name. The leak was allegedly intended to avenge criticism of the White House's rationale for war with Iraq by Plame's ex-diplomat husband Joseph Wilson.
Plame meanwhile, has filed a civil suit against Cheney, arguing that her outing, which she alleges he orchestrated, violated her constitutional rights.
Libby had faced up to 25 years in prison, but the two-and-a-half year sentence was still considered by pundits to be harsh, especially since special prosecutor Patrick Fitzgerald had not indicted him on the more serious federal crime of outing an undercover intelligence officer.
The trial exposed a White House allegedly deeply involved in managing the news, manipulating reporters, and exaggerating intelligence on Iraq's weapons of mass destruction programme.
The scandal erupted after Wilson, a former US ambassador to Gabon, was sent to Niger in February 2002 to investigate claims Saddam Hussein tried to buy uranium for nuclear bombs but concluded it was doubtful such transfers took place.
The claim still found its way into Bush's annual state of the union address a year later, prompting Wilson to stew for six months before unleashing a New York Times article in which he warned that senior US officials may have ignored data which contradicted the case for war.
On July 7, 2003, the White House admitted the Niger claim rested on flawed intelligence, and should never have made it into the speech.
Conservative newspaper columnist Robert Novak then reported that "two senior administration officials" told him that Plame, Wilson's wife, was a CIA operative working on weapons of mass destruction and had suggested his mission.
Wilson then accused White House officials of deliberately sabotaging his wife's cover.