Video report by ITV News Correspondent Sejal Karia
Commissioner Dany Cotton was due to retire in April next year, but will now step down at the end of this month.
In a through the brigade, Ms Cotton said: "I feel honoured to have served London and I will do all I can to assist the safe transition of my responsibilities to the new London Fire Commissioner when they are appointed."
The 50-year-old started serving at Wimbledon fire station in 1988 and worked her way up to become the UK’s first female station officer after 12 years.
In 2017 she became LFB’s first female Commissioner, immediately encouraging more women to sign up in a bid to make the capital’s brigade more diverse.
Her 32-year career was blighted with tragedy.
Shortly after joining LFB, she attended the Clapham Rail disaster in which 33 people died.
London Mayor Sadiq Khan has thanked Ms Cotton for her service, adding work to appoint a new fire commissioner will begin shortly with a plan to implement the findings of the report into the Grenfell Tower fire.
'Change in leadership is needed to keep Londoners safe', Grenfell survivors say
A statement from the organisation said: "This change in leadership is needed to keep Londoners safe. Sir Martin Moore-Bick raised serious concerns that the London Fire Brigade was an institution at risk of not learning the lessons of Grenfell.
"The phase one report has important recommendations for the LFB. The incoming commissioner must ensure that they move swiftly to ensure those recommendations are implemented.
"The LFB leadership must be determined in their efforts to ensure the lessons of Grenfell are learnt."