Andy Roe made the decision just minutes after taking over the brigade’s response to the devastating fire which killed 72 people and left many more homeless in June 2017.
The public inquiry set up to investigate the fire found the “stay put” policy contributed to the death toll, while also pointing a finger at the flammable cladding around the tower block.
The former soldier became a firefighter in 2002 and became deputy commissioner for operations last month.
His appointment by Sadiq Khan, the mayor of London, comes after his predecessor stepped down some months early, amid criticism of LFB’s response to the Grenfell blaze.
Dany Cotton, the capital’s first female fire chief, had been due to retire in April 2020 after 32 years of service.
Mr Roe said: ”We have some real challenges ahead, but I’ll be working tirelessly with the brigade, the mayor and London’s communities to ensure we deliver on the recommendations of the Grenfell Tower Inquiry report.
“I’m looking forward to leading the brigade through a period of transformation and delivering a workforce that truly reflects the diverse city we serve.”
Mr Khan added: “The Grenfell Tower Inquiry report made it clear there were institutional failures that meant, while firefighters performed with great courage and bravery, the overall response to the disaster was not good enough, and there are significant lessons for LFB.”
The LFB said that following consultation with City Hall, it had been agreed that Ms Cotton, 50, would bring forward her retirement to the end of this year “to enable a timely handover” to the next commissioner.
She had previously resisted multiple calls for her to resign and welcomed the report’s recommendations, saying they would be “carefully and fully” considered by senior officers.
Additional reporting by Press Association