Private homes have been used by Ealing Council to house 43 families at a cost to taxpayers of £70,000 a month.
The £828,000 a year total applies to rented homes let through the Local Housing Allowance scheme - including the Saindi family, who were controversially given a seven-bedroom mansion in Acton.
All but nine of the 43 private properties used by the council cost more than £1,000 each month, including one at £2,903 and another at £2,567.
The figures - revealed through a Freedom of Information Act request obtained by the Gazette - come as it emerged that Ealing Council was ranked fifth slowest in the country last year for paying out housing benefits.
All the Ealing families have been placed in rented flats and houses since April this year, when the Local Housing Allowance scheme started up. It is used to provide emergency housing to people when no council flats are available, with cash coming from central Government.
New restrictions on rental costs are set to be brought in next year following the scandal of the Saindi family, who were placed in a house costing more than £12,000 a month.
But Labour opposition leader Julian Bell said questions remained over whether families are being housed in expensive properties with more bedrooms than they need.
He said: "I'd want to look at all of the cases to see where there are problems. People are outraged when they're waiting for years and years in overcrowded conditions and there are people getting luxury accommodation.
"The council needs to make sure it's considering value for money issues when it's making these decisions, and the figures indicate that there is work still to be done."
He added that the speed at which benefits are paid out was an ongoing problem for which there could be "no more excuses".
A spokeswoman said the council had been encouraged by the government to use private housing where needed in place of emergency bed and breakfast accommodation, which can be as expensive.
She said: "The council has no discretion on how to administer housing benefit or what the maximum rent level is under this scheme. Following changes in government policy last April, the council is no longer able to cap rents.
"The council has expressed its desire that the government urgently review the scheme to end the publication of maximum rent levels. This would enable all councils to be able to negotiate more competitive rent agreements without being undermined."
Waiting times for housing benefit have been cut to 34 days this year, she said, and further improvements are expected.