Dominic Cummings has been seen carrying boxes away from Downing Street after the BBC reported he had left his position with immediate effect.
Boris Johnson's top advisor was pictured as he chose to walk out of the front entrance of No10 carrying a large box of his belongings.
The news was announced by the broadcaster's political editor, Laura Kuenssberg, in a series of tweets on Friday afternoon.
"Dominic Cummings has now decided to leave Number 10 today for good - (subtle hint walking out with a box - Lee Cain also now out from today)," she wrote.
"There was a conversation btw the 2 of them and the PM at lunchtime today where it was decided after upset in the team and difficult week, best to go immediately.
"This was all a slow burning fuse but exploded fast when it finally happened! End of a very torrid era."
It comes after rumours that Boris Johnson's most senior adviser was set to leave his Downing Street position by Christmas.
The controversial adviser told the BBC that "rumours of me threatening to resign are invented" after speculation that he would quit after the resignation of communications director Lee Cain.
Lee Cain announced late on Wednesday he was quitting as director of communications amid a internal power struggle in Downing Street.
In his resignation statement, Mr Cain confirmed he had been offered a promotion to the key position of the Prime Minister’s chief of staff.
However it ran into immediate resistance, with Mr Johnson’s fiancee Carrie Symonds – who has clashed in the past with Mr Cummings – reportedly strongly opposed to the appointment.
Mr Cummings and Mr Cain are close political allies, having worked together since the Brexit campaign. Mr Cummings was said to be unhappy with the way his friend had been treated.
Mr Johnson's right-hand man controversially became a focus of attention when he broke lockdown rules in April by driving to his parent's house in Durham, then to Barnard Castle, while his wife was suffering from coronavirus symptoms.
Cummings then held a disastrous press conference in Downing Street's rose garden where he sought to defend his actions.
Sources told multiple media outlets Mr Cummings had decided to leave with immediate effect, and would not be returning to Downing Street.
Despite questions from journalists, No10 had never actually formally confirmed the top aide has or will quit.
But a source told the BBC's Laura Kuenssberg Mr Cummings was now gone "for good".
