The council’s leadership team agreed the move, nearly a year after the Grenfell Tower disaster which claimed the lives of 72 people.
The director of housing, Doug Goldring, said the council would do its own independent tests of the doors and would do more tests half way through the project - making test results publicly available.
He said the council will be surveying estates across the borough and it is likely that 4,000 doors and frames will be replaced at an estimated cost of £1,000 each.
It will replace the front entrance fire doors and door sets at its homes across the borough.
The decision comes after the leadership team stood in silence for 72 seconds in memory of people who died at the council-owned Grenfell Tower in North Kensington.
A report presented to the leadership team said the council is working “to make sure all its homes are fire safe”. It said the council is continuing “to review the fire safety of its homes and to bring them up to the most stringent standards wherever there are issues”.
The doors will be fitted, even if they are not required by fire risk assessments, the council pledged.
The report said: "Whilst the door-sets that are proposed to be replaced under this programme are not necessarily deficient in terms of the Fire Risk Assessment, replacing them will bring the flat entrance doors up to current Building Regulation standards. This is not currently a legislative requirement, but this may change following the completion of the current building regulations review”.
'I don't feel that there is a price on life'
Amanda Beckles from the Grenfell Tower Community Monitoring project told the counci's Cabinet members: "After what I witnessed last year I don't feel that there is a price on life."
Kim Taylor-Smith, who has responsibility for housing and Grenfell said that was also the council's view.
Council leader Elizabeth Campbell told the meeting on Wednesday (June 6): "It's really important we get this right. We really must ensure that these doors really fit and work."
Councillor Pat Mason (Labour, Golborne) told the Cabinet members he thought "the planning stage is not solid, it's on quicksand. We need to firm up this planning stage."
Councillor Campbell told him the council knew what the costs were. Mr Goldring said it had looked at the issues "very quickly" after Grenfell.
The council promised that residents will be “fully involved in selecting door types and colours – where planning regulations and conservation rules allow”.