Hackney Council has published online details of items of expenditure over £500, in line with government guidance set in place last year.
With 31 January as the deadline, Hackney and other remaining councils had only a couple of weeks left to comply.
Mayor of Hackney, Jules Pipe, said: “Hackney Council has worked hard over the past decade to achieve a reputation for excellent financial management.
“As the only council to have ever achieved five years of consecutive council tax freezes, alongside making the highest efficiency savings in London, and investing in continuous service improvement, Hackney has built a foundation of efficiency and high quality services.
“As a council, we feel it is vital that we are open and transparent about where and how we spend money and are therefore now publishing the details of all expenditure over £500.”
The call for financial openness was announced in June last year by Eric Pickles, the Secretary of State for Communities and Local Government.
He said: “Getting council business out in the open will revolutionise local government. Local people should be able to hold politicians and public bodies to account over how their hard earned cash is being spent and decisions made on their behalf. They can only do that effectively if they have the information they need at their fingertips.
“The public should be able to see where their money goes and what it delivers. The swift and simple changes we are calling for today will unleash an army of armchair auditors and quite rightly make those charged with doling out the pennies stop and think twice about whether they are getting value for money.”