Xansa has begun its services work with the Department of Health.
Sir Nigel Crisp, chief executive of the NHS, officially launched the joint venture service, which will be known as NHS Shared Business Services.
The initiative is the first ever between the private sector and the Department of Health, and will provide finance and accounting services to NHS organisations.
Xansa said the service would offer NHS organisations the benefits of guaranteed cost savings, reduced capital expenditure and best in class services, while enabling some £224m to be reinvested into frontline patient care.
Around 230 NHS staff based in the existing shared financial services centres in Leeds and Bristol will transfer to Xansa. The software to run financial transaction processing and e-commerce for the NHS will be provided by Oracle, which will provide Oracle Financials 11i to all NHS trusts.