The pound;12 million Manchester academy, which was officially opened last week, has an agreement with the nearby William Hulme's grammar, allowing gifted sixth-formers to take subjects it does not offer.
Staff and lesson plans will also be shared between the two schools as part of the deal, one of the first official partnerships signed between a leading private school and an academy.
It follows a call last week by Jacqui Smith, schools minister, for the country's leading private schools to contribute more to the state sector.
She told the Headmasters' and Headmistresses' Conference, a meeting of 246 independent schools, that they should strike up partnerships with local comprehensives or risk losing their charitable status.
Stephen Patriarca, head of the pound;7,100-a-year William Hulme's grammar, said: "Manchester academy is trying to bring educational aspiration to one of the most deprived communities in the country. These are the same communities which we draw our pupils from, we share many of the same concerns, so it makes sense to formalise that relationship."
Manchester academy, which is sponsored by the United Learning Trust, an Anglican charity, opened in 2003, although an official ceremony marking the completion of its new building was held last week, attended by Lord Carey, the former Archbishop of Canterbury.
A new sixth form was added to the academy, which replaced Ducie high school, but its range is limited. One pupil is now being sent to William Hulme's for chemistry tuition and others are expected to follow this term.
Mr Patriarca said a "nominal fee" had been agreed to cover tuition costs.
The two schools are also applying to the Government through its Pounds 1m-a-year independentstate school partnership for cash to support more projects, including exchanging trainee teachers and classroom materials.
Kathy August, Manchester academy principal, said the partnership would allow the school to increase the pace of improvements.
The announcement follows a similar deal struck between the pound;20,000-a-year Millfield school in Somerset, the UK's largest mixed boarding school, and the City academy, Bristol.
Marlborough college, the pound;21,000-a-year boarding school in Wiltshire, which numbers Princess Eugenie among its pupils, has links with an unnamed academy in the Home Counties.