Inspectors said Chessington Community College has remained "good", pointing to a positive environment and improving results.
Ofsted has just released its report following a short visit at the beginning of May.
It praised the leadership team, writing it had fostered a "caring, welcoming and supportive environment where pupils feel safe, attend well and are ready to learn."
Also mentioned were the improvement in results and "substantial" improvement in attendance since the previous visit in 2015, as well as an improvement in pupils' attitudes towards learning - in part due to senior leaders holding staff "rigorously" to account.
In a letter to parents, headteacher Ash Ali thanked parents for their support, adding: "We are now not only a solidly 'good' school with many confirmed exceptional features, but also a school that can be proud of itself.
"For me, that students are happy, feel completely safe, have cracking lessons, achieve well and love coming to school are what really matters.
"We will not rest on our laurels and will continue to strive to being the very best we can be. This is a good milestone on that journey."
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