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 Garissa County
| School Code | School Name | Category | Type | |
| 1 | 45801130 | MUZDALIFA INTERGRATED GIRLS HIGH SCHOOL | County | Girls |
| 2 | 45804101 | SHURIE SECONDARY SCHOOL | County | Boys |
| 3 | 45804102 | YUSUF HAJI GIRLS SECONDARY SCHOOL | County | Girls |
| 4 | 45805101 | MODOGASHE SECONDARY SCHOOL | County | Boys |
| 5 | 45805102 | BENANE SECONDARY SCHOOL | County | Mixed |
| 6 | 45806101 | BURA SECONDARY SCHOOL | County | Boys |
| 7 | 45806103 | NANIGHI SECONDARY SCHOOL | County | Boys |
| 8 | 45806202 | ALINJUGUR SECONDARY SCHOOL | County | Mixed |
| 9 | 45815101 | DADAAB SECONDARY SCHOOL | County | Boys |
| 10 | 45815201 | KULAN SECONDARY SCHOOL | County | Boys |
| 11 | 45815301 | DERTU GIRLS SECONDARY SCHOOL | County | Girls |
| 12 | 45816101 | BALAMBALA SECONDARY SCHOOL | County | Boys |
| 13 | 45821101 | HULUGHO BOYS’ SECONDARY SCHOOL | County | Boys |
| 14 | 45821102 | HULUGHO GIRLS SECONDARY SCHOOL | County | Girls |