The 68-year-old man, a figure of right-wing populism in the United States and director of Donald Trump's successful campaign in 2016, will experience his sentence in October.
The jury of a federal court in Washington deliberated for less than three hours on Friday to conclude that he was guilty on the two charges against him.
He faces between a month and a year in prison for each of these counts.
Even after being ousted from the White House in August 2017, Steve Bannon remained close to Donald Trump and spoke with him the day before the January 6, 2021 attack on Congressional headquarters.
To find out the nature of their discussions, the parliamentary commission of inquiry responsible for shedding light on the role of the former president in this coup had summoned Steve Bannon to testify and produce documents.
He refused, citing the right of presidents to keep certain conversations secret, which led to him being charged with "obstructing" the work of Congress.
- Silent Defense -
At the opening of the proceedings on Tuesday, prosecutor Amanda Vaughn accused Steve Bannon of believing himself "above the law".
Mr Bannon 'ignored orders to comply, even after Congress rejected his pretenses, and brushed off numerous warnings that he would face prosecution if he did not comply with the subpoena as he had to do it," added Amanda Vaughn.
According to her, the commission had legitimate reasons to believe that he, like others close to the president, could have information on the links between Donald Trump and his supporters who stormed the Capitol as parliamentarians certified the Democrat Joe Biden's presidential victory.
The defense did not produce witnesses at the trial, which began Monday with the selection of jurors, and Steve Bannon did not speak himself to defend himself.
His lawyer, Evan Corcoran, however, denounced political prosecution, assuring that "no one (did) ignore the subpoena" and that negotiations had even taken place with the commission concerning his date of testimony.
As his trial approached, Steve Bannon had agreed to cooperate with the parliamentarians. The prosecutors had denounced "a last minute reversal in order to avoid" a conviction and the judge in charge of the case had wished to maintain the trial.
A vocal critic of the political establishment, Steve Bannon is closely associated with far-right ideas, which he promoted directly to Donald Trump when the business magnate entered the White House in 2017.
He previously ran the controversial Breitbart news site, a hub of the "alternative right", a movement associated with certain conspiratorial theses and comprising a number of militants convinced of the superiority of the white race.
