The contract, worth £24 million over five years, has been awarded to Capita Managed Services.
Capita will take over council tax and business rates collection, benefits administration, payroll and pensions administration. There will be performance related payments if it meets targets for revenue collection.
Under the contract, 170 staff will transfer to Capita on their existing terms and conditions. The company plans to set up a centre in Bromley from which it will supply services to public sector organisations throughout the south east, the FT reports.
Bromley treasurer David Bartlett said: 'This move will help us to protect the position of our employees, whose work is shrinking as schools opt out and we contract out other functions'.
It will also mean a more cost effective service, he said. Bromley expects to save £1m by contracting out, the paper reports.