Figures revealed through a freedom of information request show Homes for Lambeth (HfL) shelled out £970,229 between January 2021 and December 2022 on workspace at WeWork Waterloo.
WeWork Waterloo is part of the Southbank Place development on the site of the Shell Centre in York Road.
Labour-led Lambeth Council announced it was shutting down HfL in November 2022 after the company started work on just 65 homes in five years. The decision followed an independent report into affordable housing in the borough, which branded HfL's attempts to build homes "very poor".
Cllr Scott Ainslie, Lambeth Green group's co-leader, said the council needed to launch an investigation into the decision to rent the workspace. He said: "It really looks like Lambeth has no control over finances whatsoever. They're asking people to pay more council tax but they're leaking millions out the door.
"It has been a complete waste of money that should never have been signed off in the first place. There has been absolutely no financial control over this decision and there needs to be a full investigation into that decision."
He added that Lambeth's rental of the workspace was all the more confusing when the council's Phoenix House offices in Vauxhall, only a 30-minute walk away from WeWork Waterloo, were lying empty.
Cllr Ainslie said: "Why didn't Lambeth look into other options for buildings that they could have used? Phoenix House, the council's offices in Vauxhall, is sitting empty."
The full amount HfL will end up paying for the WeWork offices is likely to be higher than £1 million as the company's lease on the workspace doesn't end until 31 March 2023. Lambeth Council's decision to release the information follows a nine-month battle by the Local Democracy Reporting Service.
The council were originally asked for details of how much HfL had spent on WeWork desk space in a Freedom of Information request from April 2022. Lambeth replied that the information was "commercially confidential" and refused to hand it over. On appeal, Lambeth stuck to its refusal to disclose the information.
The Local Democracy Reporting Service then complained to the Information Commissioner's Office (ICO) – an organisation responsible for upholding rights to information. In December 2022, the ICO ruled that Lambeth should have provided the information about the cost of desks and ordered it to reveal the details within 35 days.
In its 2020 business plan, HfL promised to build more than 1,000 homes by 2025 but work on most of these promised homes never began.
One of HfL's stalled schemes involves building new homes in Waterloo's Wootton Street.
A Lambeth Council spokesperson said: "The decision about the letting of office space was made by the previous executive team at Homes for Lambeth (HfL).
"An independent review of Lambeth's housing programmes, commissioned by the council last year, has recommended that HfL be closed down and its functions brought back into the council. Notice has been given on the HfL office lease, and it will end in March.
"The council has accepted all the recommendations of the Kerslake Review and is working to deliver the detailed action plan agreed by the cabinet in December."