Rony Salazar, 18, fled El Salvador at 14 and joined Caterham High School in Clayhall in the last term of Year 10 without any knowledge of English.
After learning the language for just two weeks, he passed all his GCSEs.
Rony has now achieved three Bs at A-level.
He is set to take up an apprenticeship at Barking and Dagenham Council’s housing department.
Rony said: “I only did one month of year ten.
“I came here with no English. It’s about the hardest thing.
“I knew if I failed, I would have to redo it. I am very proud of myself.
“I studied so much, my head would be full, and I got a bit overwhelmed; it is a good idea to have a balance, that’s what my business teacher said.”
He finds British schools “very different” from those in El Salvador but is proud of his success.
He advised other A-level students: “Seize the moment, focus a lot.
“I did two or three hours a day, I tried to regulate it.
“Leave some time for yourself to study and with your parents.”
Headteacher Belinda Chapple praised Rony’s resilience and the school’s supportive environment.
She said: “There are individual stories which have shown a huge amount of resilience.
“We are very careful about making sure the children get the individual support they need.
“We have got really good pastoral support in our sixth form here.
“We really hone in and where they need that support.”
