The network’s CEO called the 64 year old, who was Breitbart’s executive chairman, a “valued part of our legacy”.
A statement released on the website said: “Stephen K Bannon has stepped down from Breitbart News Network, where he served as Executive Chairman since 2012.”
Breitbart CEO Larry Solov, said: “Steve is a valued part of our legacy, and we will always be grateful for his contributions, and what he has helped us to accomplish.”
Mr Bannon said: “I’m proud of what the Breitbart team has accomplished in so short a period of time in building out a world-class news platform.”
The website’s financial backers and political supporters pulled out following the numerous claims Mr Bannon made against US President Donald Trump in Michael Wolff’s book Fire and Fury: Inside the Trump White House, published on Friday.
Mr Bannon, who was previously Mr Trump’s closest confidant, questioned his former boss’ mental stability, claimed those close to the President described him as a “moron, an idiot” and his deputy chief of staff said working with him is like “trying to figure out what a child wants”.
Backers of the right-wing website, including the billionaire Mercer family, were not happy with the clash.
During the US election trail Breitbart became one of the go-to sources of information for those supporting the Trump campaign.
The Breitbart board, including the Mercers, Larry Solov and Susie Breitbart, have reportedly spent the past few days debating whether Mr Bannon needed to go.
All board members were united in voting for him to be ousted and Mr Bannon was contacted on Monday to be told he had to go, according to the Wall Street Journal.
Former investment banker and US Navy officer Mr Bannon was a founding member of the board of Breitbart News in 2007.
He became executive chair of its parent company in 2012 after founder Andrew Breitbart died.
Breitbart then went down a more nationalistic route, with Mr Bannon describing the site in 2016 as “the platform for the alt-right”.
He was appointed chief executive of Mr Trump’s presidential campaign in 2016, leaving Breitbart and becoming chief strategist for Mr Trump when he won.
In August last year he was fired following a United the Right rally in Charlottesville which became violent.
Mr Trump accused “many sides” for the violence, under the guidance of Mr Bannon, which resulted in him being sacked.
The pair were reportedly still in close contact following that, until the release of Fire and Fury, which prompted a public slanging match between the two.
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Mr Bannon was reportedly paid a $191,000 (£141,000) annual salary at Breitbart and earns $353,000 (£260,700) more from three other positions in companies backed by the Mercer family.