Mr Bannon, formerly the head of the populist right-wing, Breitbart News website, will join high-level discussions about national security.
The order was signed on Saturday.
The director of national intelligence and the joint chiefs will attend when discussions pertain to their areas.
Following criticism of the Bannon move, White House press secretary Sean Spicer said on Monday that CIA Director Mike Pompeo would be added to the top circle of national security advisers.
Last week, Mr Bannon described the US mainstream media as "the opposition party", saying it should "keep its mouth shut".
Go to link