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 secondary schools in Nandi County:
| KNEC CODE | NAME | TYPE | CATEGORY | |
| 1 | 29513102 | ACK ST. MARK’S KIMINDA SECONDARY SCHOOL | Mixed | County |
| 2 | 29513202 | CHEPKUMIA SECONDARY SCHOOL | Mixed | County |
| 3 | 29513208 | AIC KIBORGOK GIRLS SECONDARY SCHOOL | Girls | County |
| 4 | 29513301 | KAPCHEMOIYWO GIRLS SECONDARY SCHOOL | Girls | County |
| 5 | 29513304 | KAPKAGAON SECONDARY SCHOOL | Girls | County |
| 6 | 29523102 | KAPSENGERE SECONDARY SCHOOL | Mixed | County |
| 7 | 29523109 | KEMELOI GIRLS SECONDARY SCHOOL | Girls | County |
| 8 | 29523112 | BISHOP MAKARIOS BOYS – KESENGEI | Boys | County |
| 9 | 29523114 | ST. ANNE’S GIRLS’ KAPKEMICH | Girls | County |
| 10 | 29523204 | FR. MAIR GIRLS SECONDARY SCHOOL | Girls | County |
| 11 | 29523301 | ACK ST. MARK’S KAPTUMO BOYS HIGH SCHOOL. | Boys | County |
| 12 | 29523311 | A.C.K KAPSOO GIRLS’ SECONDARY SCHOOL | Girls | County |
| 13 | 29540101 | KABIYET BOYS SECONDARY SCHOOL | Boys | County |
| 14 | 29540107 | EISERO GIRLS SECONDARY SCHOOL | Girls | County |
| 15 | 29540119 | ACK ST.MATHEWS GIRLS SECONDARY SCHOOL-SEPTONOK | Girls | County |
| 16 | 29540203 | ST. TERESA OF AVILA GIRLS – NDALAT | Girls | County |
| 17 | 29540207 | ST.BRIGITTA GIRLS HIGH SCHOOL | Girls | County |
| 18 | 29541102 | SOCHOI SECONDARY SCHOOL | Boys | County |
| 19 | 29541103 | SOCHOI A.I.C GIRLS SECONDARY SCHOOL | Girls | County |
| 20 | 29541203 | TAITO K.T.G.A SECONDARY SCHOOL | Mixed | County |
| 21 | 29541204 | ST. ELIZABETH GIRLS SECONDARY SCHOOL CHEPKUNYUK | Girls | County |
| 22 | 29541205 | KABOTE ADVENTIST SECONDARY SCHOOL | Mixed | County |
| 23 | 29542103 | GOT NE LEL SECONDARY SCHOOL | Girls | County |
| 24 | 29542204 | ALL SAINTS KAPKENO GIRLS HIGH SCHOOL | Girls | County |
| 25 | 29542301 | TINDERET SECONDARY SCHOOL | Boys | County |
| 26 | 29542305 | MOMBWO GIRLS’ SECONDARY SCHOOL | Girls | County |
| 27 | 29542401 | CHEMASE SECONDARY SCHOOL | Mixed | County |
| 28 | 29542403 | KAPSIGILAI GIRLS’ SECONDARY SCHOOL | Girls | County |
| 29 | 29579203 | A.I.C KAMOIYWO GIRLS SECONDARY SCHOOL | Girls | County |
| 30 | 29579301 | KAPTEL BOYS HIGH SCHOOL | Boys | County |
| 31 | 29579303 | ST. PAUL’S ACK GIRLS SECONDARY SCHOOL- KAPTEL | Girls | County |
| 32 | 29579603 | A I C KOSIRAI GIRLS SECONDARY SCHOOL | Girls | County |
| 33 | 29579801 | MOI HIGH SCHOOL , SIRGOI | Boys | County |
| 34 | 29579803 | ST FRANCIS CHEPTARIT SECONDARY SCHOOL | Girls | County |