County secondary schools in Kenya form the third tier after national and extra-county schools respectively.
Most of Kenyan learners are absorbed by these schools.
Admission to county schools is done online by the Ministry of Education.
They are either mixed or single-sex.
Here is a list of county schools found in Nyamira County:
| School Code | School Name | Type | Category | |
| 1 | 43706103 | NYAMAIYA SECONDARY SCHOOL | Mixed | County |
| 2 | 43706112 | MOTAGARA GIRLS SECONDARY SCHOOL | Girls | County |
| 3 | 43706122 | MASOSA MIXED SECONDARY SCHOOL | Mixed | County |
| 4 | 43706129 | MARANI P.A.G GIRLS SECONDARY SCHOOL | Girls | County |
| 5 | 43706135 | GEKOMONI SECONDARY SCHOOL | Mixed | County |
| 6 | 43715101 | ESANI SECONDARY SCHOOL | Mixed | County |
| 7 | 43715108 | RIGOMA SECONDARY SCHOOL | Girls | County |
| 8 | 43715114 | OMOYO GIRLS HIGH SCHOOL | Girls | County |
| 9 | 43720101 | MECHEO SDA MIXED SECONDARY | Mixed | County |
| 10 | 43720103 | MANGA GIRLS HIGH SCHOOL | Girls | County |
| 11 | 43720104 | ST. THOMAS MOORE | Mixed | County |
| 12 | 43720108 | ST. GONZAGAGONZA ISOGE | Mixed | County |
| 13 | 43720117 | ERONGE SDA SECONDARY SCHOOL | Mixed | County |
| 14 | 43722132 | MANGA GIRLS MODEL SCHOOL | Girls | County |
| 15 | 43728102 | GEKENDO SECONDARY SCHOOL | Boys | County |
| 16 | 43728106 | IKONGE P A G SECONDARY SCHOOL | Girls | County |
| 17 | 43728107 | IKONGE BOYS SECONDARY SCHOOL | Boys | County |
| 18 | 43728111 | ST. JOSEPH’S BIEGO SECONDARY SCHOOL | Mixed | County |
| 19 | 43728114 | KIABONYORU BOYS SECONDARY SCHOOL | Boys | County |
| 29 | 43728129 | KIABONYORU GIRLS SECONDARY SCHOOL | Girls | County |
| 21 | 43728207 | NYAMUSI GIRLS SECONDARY SCHOOL | Girls | County |
| 22 | 43728209 | MOGONGO GIRLS’ SECONDARY SCHOOL | Girls | County |
