Waldegrave School has been named among the top 100 non-selective schools in the country.
The results are based on five or more good GCSE passes, including English and maths, and on student progress.
Headteacher Philippa Nunn told staff she was extremely proud.
She said: “This sort of level of attainment does not come easily without a great deal of commitment, care and hard work from both teachers and students. We are delighted to be named the best 11 to 16 state school in the country. We are certainly not coasting.”
Waldegrave has also been ranked the top state school without a sixth form in the country, in the Sunday Times Parent Power Survey.