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 Trans Nzoia County:
| KNEC CODE | NAME | TYPE | CATEGORY | |
| 1 | 23503301 | SABOTI SECONDARY SCHOOL | Boys | County |
| 2 | 23503302 | ST. MARY’S MACHEWA SECONDARY SCHOOL | Mixed | County |
| 3 | 23503310 | IMMACULATE HEART GIRLS HIGH SCHOOL SABOTI | Girls | County |
| 4 | 23528103 | KAPSARA SECONDARY SCHOOL | Mixed | County |
| 5 | 23528104 | ST CHRISTOPHER’S SCHOOL | Boys | County |
| 6 | 23528107 | WIYETA SECONDARY SCHOOL | Girls | County |
| 7 | 23528109 | ST. PAUL’S BOYS HIGH SCHOOL-SINOKO | Boys | County |
| 8 | 23528133 | HUTUTU FRIENDS GIRLS SECONDARY SCHOOL | Girls | County |
| 9 | 23528137 | IMMACULATE CONCEPTION GIRLS HIGH SCHOOL-MUKUYU KIT | Girls | County |
| 10 | 23528201 | ST. FRANCIS BOYS HIGH SCHOOL SUWERWA | Boys | County |
| 11 | 23528206 | ST PETERS MITO MBILI GIRLS SECONDARY SCHOOL | Girls | County |
| 12 | 23528208 | ST BENEDICTS SECONDARY SCHOOL KAPSIGILAI | Mixed | County |
| 13 | 23528214 | ST FRANCIS GIRLS HIGH SCHOOL – SUWERWA | Girls | County |
| 14 | 23528216 | A.I.C KIPKEIKEI GIRLS HIGH SCHOOL | Girls | County |
| 15 | 23529101 | KOLONGOLO SECONDARY SCHOOL | Boys | County |
| 16 | 23529102 | FRIENDS BOYS SCHOOL – KWANZA | Boys | County |
| 17 | 23529104 | NAMANJALALA SECONDARY SCHOOL | Mixed | County |
| 18 | 23529105 | BISHOP ALEXANDER MUGE SECONDARY SCHOOL | Girls | County |
| 19 | 23529106 | GIDEA SECONDARY SCHOOL | Mixed | County |
| 20 | 23529108 | KOBOS SECONDARY SCHOOL | Boys | County |
| 21 | 23529110 | ST. MAURICE HIGH SCHOOL – LUNYU | Boys | County |
| 22 | 23529122 | ST. MICHAELS GIRLS LIYAVO GIRLS’ DAY SECONDARY SCH | Girls | County |
| 23 | 23529131 | ST. FRANCIS KOLONGOLO GIRLS HIGH SCHOOL | Girls | County |
| 24 | 23529135 | ST. PATRICKS’ SECONDARY SCHOOL – MAKUNGA | Mixed | County |
| 25 | 23529141 | ST. MAURICE GIRLS HIGH SCHOOL-LUNYU | Girls | County |
| 26 | 23529150 | AIC KOBOS GIRLS HIGH SCHOOL | Girls | County |
| 27 | 23572101 | SABWANI SECONDARY SCHOOL | Girls | County |
| 28 | 23572208 | CHEPSALEI SECONDARY SCHOOL | Mixed | County |
| 29 | 23574113 | ST. TERESA’S BIKEKE GIRLS SECONDARY SCHOOL | Mixed | County |
| 30 | 23574123 | NYABOMO SDA SECONDARY SCHOOL | Mixed | County |
