Sexist and racist abuse in London Fire Brigade was seen as 'banter', according to an independent review.
London Mayor Sadiq Khan said the culture review of the service contains "abhorrent" details and "must be nothing short of a watershed moment".
He said London Fire Brigade (LFB) must be trusted to protect all Londoners and be a workplace free from discrimination, unfairness and inequality where people of all backgrounds can thrive.
The review, led by Nazir Afzal, a former chief crown prosecutor for the North West, refers to a "toxic culture" and a conclusion that finds the organisation "institutionally misogynist and racist".
Mr Khan said: "The findings of Nazir Afzal OBE's review must be nothing short of a watershed moment for the London Fire Brigade.
"The details published today of institutional misogyny, racism and discrimination are abhorrent.
"Londoners, including firefighters and other staff, have been let down by those who should have supported them have every right to be angry, as I am.
"I fully supported the fire commissioner, Andy Roe, in commissioning this review and we both agree that all of its recommendations and findings must be acted upon with urgency and conviction to rebuild public trust and the confidence of LFB staff and firefighters who have been failed for far too long."
Mr Khan said he is confident that Mr Roe recognises the scale of the problems and is the right person to lead the "deep-rooted reform needed of the culture and systems within the brigade".
He added: "The Fire Commissioner knows he has my full support in making the significant and necessary changes to root out all those found to be responsible for sexism, racism, misogyny, homophobia, bullying or harassment - and to support members of staff to speak out.
"Some of that work has already started with a new independent team investigating complaints and a pledge to scrutinise firefighter interactions with the public through Body Worn Video.
"But more must be done and at pace.
"Huge changes to policies, procedures and equipment since I appointed this new Fire Commissioner mean that the London Fire Brigade is now better prepared and equipped to fight fires and keep Londoners safe.
"But for the LFB to be trusted to serve and protect all Londoners it must be a workplace free from discrimination, unfairness and inequality where people of all backgrounds can thrive.
"That's why I will continue to support and hold the Fire Commissioner to account on delivering all the improvements needed."
Anne Clarke, chairwoman of the London Assembly Fire, Resilience and Emergency Planning Committee, said: "This toxic culture in parts of the Brigade threatens to overshadow the efforts of thousands of dedicated firefighters doing incredible work every day to keep Londoners safe.
"The London Fire Commissioner has told us he is aware of the scale of the challenge and we call on him to take forward recommendations from the culture review with a matter of urgency."
Susan Hall, leader of the GLA Conservatives, said: "I am shocked and saddened by the findings of this report.
"These horrific cases of misogyny, racism and bullying are completely unacceptable and it is deeply concerning how widespread and severe this behaviour has been.
"Sadiq Khan has led the Met Police and the London Fire Brigade for six years, both of which have seen a culture of abusive and appalling behaviour develop under his watch.
"The Mayor needs to stop sitting on the sidelines and take immediate action to address these issues."
Sarah Jones, shadow minister for policing and the fire service, said the review has revealed "appalling details of racism, misogyny, homophobia and discrimination within the London Fire Brigade that should have no place in the Fire Service".
She said: "Our thoughts are with those dedicated firefighters who have suffered such horrific abuse in their place of work.
"The review makes a number of welcome recommendations that must be urgently implemented.
"The findings leave questions to be answered about standards and culture in other fire brigades across the country and the Home Office must not step back from its responsibility to tackle this.
"The Home Office should show some leadership and make sure that any failures in standards are rooted out of the fire service and urgently addressed."
