The TES has learned that from September it will provide support to Colbayns high, Clacton, Essex, a 1,750-pupil school that has been classified as having serious weaknesses since 2000.
Colbayns will buy an integrated package from Edison covering curriculum, pupil assessment, professional development and home-school partnerships.
The company expects to finalise similar deals with four Essex primary schools later this summer.
Nick Pavitt, Colbayns' head, said Edison's service would be targeted at key stage 3 where the school has most of its problems. He will use part of his leadership incentive grant to pay for it.
Essex education authority has been advising Edison on how to tailor its methods to schools in the county for the past year.
But the company is facing local competition from Serco, another private operator, which is in talks with more than 40 Essex secondary schools about how it can help them to share best practice.
Edison originally hoped to sell its services to 15 schools but its progress in Essex has been hampered. The LEA had intended to contribute pound;50 per pupil to the deal. But its endorsement was delayed by an investigation into "issues of propriety" after its former education director, Paul Lincoln, went to work for Edison.
Iris Pummell, Essex's Conservative cabinet member for education, decided to proceed last week after being given the all-clear by the council's auditors.
The company has had a troubled year in the US with plunging share prices, the loss of a flagship contract and a financial watchdog finding that it had overstated its income.
But an Edison spokesman said the company had more than $30 million (pound;20m) in the bank and had just enjoyed its first profitable quarter since it was established in 1992.