Thirteen-year-old Sarah Nyambori Onderi from Elsa Academy in Kisii scored 442 marks to emerge the top pupil in the 2017 KCPE exams in the county.
When the Nation team arrived at the school, parents and teachers were celebrating the girl's achievement.
The soft-spoken girl said that if it was not for sickness during the examinations period, she could have scored even higher marks.
"I am very happy as I have seen that my dreams have started coming true. I achieved this through hard work and prayers," said the girl who wants to be a neuro-surgeon.
Sarah scored 97 (A) in English, Kiswahili 98 (A), Mathematics 85 (A), Science 83 (A) and Social Studies 79 (B+).
Her joyous mother, Esther Kwamboka, described her daughter as hardworking and very respectful.
Ms Elizabeth Orenge the deputy director of the school said that pupils in the institution performed very well this year.
"So far we have 19 students who have scored above 400 marks. I am very much delighted," she said.