VT Group, a defence and support service company, and Conservative-controlled Surrey council have teamed up to provide services such as curriculum support and financial consultancy.
Their company, called Four S Services, is the first of its kind and has a pound;100 million, seven-year contract in the county.
It will also aim to win work from other councils - any profits will be shared between VT (70 per cent) and Surrey council (30 per cent).
Surrey is the first successful authority to outsource services to a private company.
Last year, the Office for Standards in Education praised the council for its "many strengths and no weaknesses".
The move gives new impetus to the Government's privatisation agenda which had stalled following high-profile problems with companies running schools services in the London boroughs of Southwark, Hackney and Islington.
Mr Miliband said: "The market of school improvement services is developing fast and this is in the best interest of schools and pupils.
"There is a lot of expertise involved in this public-private partnership and lessons to be learned across the different sectors."
Steve Clarke, Four S chief executive, said the firm would give Surrey schools a wider range of high quality services.
"Schools of the future will have extended learning, family learning, and close links with health and social care agencies.
"Four S is well placed to deliver this agenda for schools."