Sadiq Khan has accused the government of "putting lives at risk" by not implementing changes recommended by the Grenfell Tower Inquiry quickly enough.
Last year, the inquiry identified 46 changes to be made to ensure the safety of residents in high-rise buildings.
But the Mayor of London has claimed the government is failing the Grenfell community due to a lack of progress.
Home Office minister James Brokenshire has said the reforms will be made in the "fastest possible time".
Mr Khan said the government "must not wait" to implement reforms that are "needed to fix a broken system", and questioned why there was no timetable for the planned changes.
The mayor added: "I am concerned that without faster action, the government and building owners are failing the Grenfell community and putting lives at risk.
"I know the Grenfell community are fearful that a similar tragedy could happen again and I share their concerns."
The recommendations made in the first phase of the inquiry touched on how buildings are designed, constructed, approved and managed and how fire and rescue services respond.
Of the 29 recommendations made to London Fire Brigade (LFB), four have so far been completed, including the introduction of smoke hoods to aid in rescues.
The mayor's office said work had "significantly progressed" on all the LFB's remaining recommendations, with the majority due to be completed by March next year.
London fire commissioner Andy Roe said the coronavirus pandemic had delayed some of the improvements.
He added: "I share the mayor's concerns that faster action is needed by the government, housing and building industries and that urgent changes do need to be made to building safety regulations."
The government has been approached for further comment.