Nicholas Kiprotich of Bishop Muge Memorial School Kimng'oror scored 424 marks to emerge top in Nandi County.
Kiprotich lives with a guardian, Joyline Yego, after he lost his parents.
"I have been performing well in school and expected to get good marks, but what I got surpassed my expectations," he said.
Kiprotich now hopes to get admission to Mang'u High School and later be a doctor.
Yego is grateful that the boy, despite the many challenges they face as a family, was able to register a remarkable performance.
Angela Chepkosgei, who garnered 423 marks from the same school, hopes to join Alliance Girls High School and pursue a career in neurosurgery later on.
Bishop Muge Memorial School Kimng'oror, a public institution, managed a mean score of 393.21, with 44 pupils getting over 400 marks.
Headteacher Sammy Sawe said the school had registered an improvement from the previous year's results where it had a mean score of 391.
In Trans Nzoia, Kitale School also produced the county's top performers, with Samson Kiago Isaboke scoring 422 marks in the class of 283 candidates.
St Joseph the Worker Hema Schools has a mean score of 398.1, with its top student, Leon Messi, getting 417 marks.
Hilltop Preparatory School posted a mean score of 380, with its top candidate, Metchelle Chebet, scoring 415 marks. Brain Wambia came second with 414 marks.
