In Kenya, extra county schools fall in the second tier after national schools. In recent years, cases have emerged where extra county schools perform better than national school.
Extra county secondary schools in kisii county are grouped into three clusters; cluster one(C1), cluster two(C2) and cluster three (C3). Kereri Girls High School, Riokindo High School, Moi Gesusu High School among other schools form cluster one schools in Kisii County.
Here is a list of best performing Extra County Secondary schools in Kisii County
| S/N | SCHOOL CODE | SCHOOL NAME | TYPE | CLUSTER |
| 1. | 40703103 | Kereri Girls High School | Girls | C1 |
| 2. | 40716103 | St.Paul’s Igonga Secondary School | Boys | C1 |
| 3. | 40719104 | Kiabigoria Secondary School | Mixed | C1 |
| 4. | 40727101 | Riokindo High School | Boys | C1 |
| 5. | 40735101 | Moi Gesusu High School | Boys | C1 |
| 6. | 40735201 | St. Charles Lwanga Ichuni Girls High School | Girls | C1 |
| 7. | 40745101 | Cardinal Otunga High School-Mosocho | Boys | C1 |
| 8. | 40703102 | Nyanchwa Boys High School | Boys | C2 |
| 9. | 40703403 | Nyamagwa Sda Secondary School | Mixed | C2 |
| 10. | 40711101 | St.Angela Sengera Girls Secondary School | Girls | C2 |
| 11. | 40716101 | E L C K Itierio Boys High School | Boys | C2 |
| 12. | 40716102 | Suneka Secondary School | Girls | C2 |
| 13. | 40716118 | E L C K Itierio Girls Secondary School | Girls | C2 |
| 14. | 40719102 | Riosiri Secondary School | Mixed | C2 |
| 15. | 40719301 | Tabaka Secondary School | Boys | C2 |
| 16. | 40723201 | Itibo Boys High School | Boys | C2 |
| 17. | 40723203 | Itibo Girls Secondary School | Girls | C2 |
| 18. | 40732206 | St. Theresa’s Nyangusu Girls Secondary School | Girls | C2 |
| 19. | 40740101 | St.Johns Nyamagwa Boys | Boys | C2 |
| 20. | 40740102 | Sameta High School | Boys | C2 |
| 21. | 40740104 | St. Mary’s Nyamagwa Girls Secondary School | Girls | C2 |
| 22. | 40716119 | Nyangoge Girls Secondaryschool | Girls | C3 |
| 23. | 40716122 | Bishop Charles Mugendi Secondary School | Mixed | C3 |
| 24. | 40719101 | Nduru Boys High School | Boys | C3 |
| 25. | 40732114 | Nyamache Secondary School | Boys | C3 |
