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 Kajiado County:
| KNEC CODE | NAME | TYPE | CATEGORY | |
| 1 | 31515105 | SAJILONI GIRLS SECONDARY SCHOOL | Girls | County |
| 2 | 31515106 | ENKORIKA SECONDARY SCHOOL | Boys | County |
| 3 | 31515108 | NKOILE BOYS HIGH SCHOOL | Boys | County |
| 4 | 31515404 | ILBISSIL GIRLS SECONDARY SCHOOL | Girls | County |
| 5 | 31515407 | METO SECONDARY SCHOOL | Mixed | County |
| 6 | 31515409 | NGATATAEK MIXED SECONDARY SCHOOL | Mixed | County |
| 7 | 31515410 | MAPARASHA SECONDARY SCHOOL | Mixed | County |
| 8 | 31545102 | ILKISONKO SECONDARY SCHOOL | Boys | County |
| 9 | 31545103 | OLCHORRO SECONDARY SCHOOL | Mixed | County |
| 10 | 31545107 | A.I.C SECONDARY SCHOOL – LOITOKITOK | Girls | County |
| 11 | 31545108 | WHITE MOUNTAIN SECONDARY SCHOOL | Mixed | County |
| 12 | 31545201 | ILLASIT SECONDARY SCHOOL | Mixed | County |
| 13 | 31545203 | COLIN DAVIES SECONDARY SCHOOL | Mixed | County |
| 14 | 31545204 | KIKELELWA SECONDARY SCHOOL | Mixed | County |
| 15 | 31545205 | ROMBO GIRLS’ BOARDING SECONDARY SCHOOL | Girls | County |
| 16 | 31545206 | ENTARARA SECONDARY SCHOOL | Mixed | County |
| 17 | 31545301 | KIMANA SECONDARY SCHOOL | Girls | County |
| 18 | 31545303 | ENKII BOYS’ SECONDARY SCHOOL | Boys | County |
| 19 | 31545306 | NAMELOK SECONDARY SCHOOL | Mixed | County |
| 20 | 31545307 | LENKISEM MIXED BOARDING SECONDARY SCHOOL | Mixed | County |
| 21 | 31566101 | MASHUURU SECONDARY SCHOOL | Boys | County |
| 22 | 31566201 | ELERAI MCK GIRLS SECONDARY SCHOOL | Girls | County |
| 23 | 31566206 | THOMAS FISH SECONDARY SCHOOL | Mixed | County |
| 24 | 31573101 | BARAKA OONTOYIE SECONDARY SCHOOL | Girls | County |
| 25 | 31573113 | OLOYIANKALANI MIXED DAY SECONDARY SCHOOL | Mixed | County |
| 26 | 31573114 | KISAJU MIXED SECONDARY SCHOOL | Mixed | County |
| 27 | 31573202 | EWUASO GIRLS SECONDARY BOARDING SCHOOL | Girls | County |
| 28 | 31573203 | PCEA ILNGAROOJ BOYS SECONDARY SCHOOL | Boys | County |
| 29 | 31573204 | PCEA KIMUKA GIRLS SECONDARY SCHOOL | Girls | County |
| 30 | 31573205 | KIBIKO SECONDARY SCHOOL | Mixed | County |
| 31 | 31573302 | PATERSON MEMORIAL SECONDARY SCHOOL | Mixed | County |
| 32 | 31573401 | OLOIBORSOIT GIRLS SECONDARY SCHOOL | Girls | County |
| 33 | 31573402 | ILOODOKILANI SECONDARY SCHOOL | Girls | County |
