| Ladbrooke Junior Mixed and Infant School117370 | Primary | Good | 18.8% | 226 |
| Knutsford Primary Academy146123 | Primary | Good | 9.3% | 438 |
| Knightsfield School138485 | Not applicable | Outstanding | 20.3% | 65 |
| Knebworth Primary and Nursery School117120 | Primary | Good | 11.3% | 390 |
| Kingswood Nursery School117076 | Nursery | Outstanding | 0.0% | 76 |
| Kingsway Junior School117168 | Primary | Good | 26.8% | 235 |
| Kingsway Infants' School117317 | Primary | Good | 18.1% | 171 |
| Kingshott School117630 | Not applicable | — | — | 403 |
| Kingshill Infant School117319 | Primary | Good | 3.7% | 206 |
| Kings Langley School139036 | Secondary | Good | 14.6% | 1,122 |
| Kings Langley Primary School117283 | Primary | Good | 8.4% | 437 |
| King James Academy Royston137656 | All-through | Good | 18.6% | 947 |
| Kimpton Primary School117118 | Primary | Expected standard | 22.9% | 133 |
| Killigrew Primary and Nursery School135528 | Primary | Good | 7.5% | 412 |
| Kenilworth Primary School117183 | Primary | Good | 29.1% | 210 |
| Katherine Warington School145890 | Secondary | Good | 13.9% | 1,113 |
| Jupiter Primary School140955 | Primary | Good | 18.1% | 397 |
| John F Kennedy Catholic School149743 | Secondary | Good | 16.9% | 1,073 |
| Jenyns First School and Nursery117087 | Primary | Good | 3.4% | 66 |
| James Marks Academy149736 | Not applicable | — | 21.4% | 62 |
| Immanuel College117657 | Not applicable | — | — | 341 |
| Icknield Walk First School117278 | Primary | Good | 10.7% | 335 |
| Icknield Infant and Nursery School117186 | Primary | Requires Improvement | 26.7% | 206 |
| Ickleford Primary School117401 | Primary | Good | 10.3% | 213 |
| Hurst Drive Primary School117180 | Primary | Good | 31.1% | 399 |
| Hunsdon Junior Mixed and Infant School117117 | Primary | Outstanding | 14.0% | 93 |
| Howe Dell Primary School117220 | Primary | Good | 15.3% | 428 |
| How Wood Primary and Nursery School117235 | Primary | Good | 12.8% | 215 |
| Hormead Church of England (va) First School117439 | Primary | Good | 12.3% | 143 |
| Homerswood Primary and Nursery School117252 | Primary | Good | 21.7% | 218 |
| Holy Trinity Church of England Primary School117428 | Primary | Good | 21.2% | 198 |
| Holy Rood Catholic Primary School146903 | Primary | Outstanding | 4.1% | 454 |
| Holwell Primary School117175 | Primary | Good | 31.7% | 397 |
| Holtsmere End Junior School117336 | Primary | Good | 37.1% | 237 |
| Holtsmere End Infant and Nursery School117377 | Primary | Good | 20.8% | 201 |
| Hollybush Primary School117263 | Primary | Requires Improvement | 37.2% | 190 |
| Holdbrook Primary School and Nursery117091 | Primary | Good | 43.9% | 210 |
| Hockerill Anglo-European College136482 | Secondary | Good | 4.8% | 903 |
| Hobletts Manor Junior School117097 | Primary | Good | 30.0% | 237 |
| Hobletts Manor Infants' School117197 | Primary | Good | 19.9% | 214 |
| Hobbs Hill Wood Primary School117368 | Primary | Good | 15.1% | 450 |
| Hitchin Girls' School137288 | Secondary | Outstanding | 7.1% | 1,357 |
| Hitchin Boys' School139154 | Secondary | Strong standard | 8.8% | 1,364 |
| Hillshott Infant School and Nursery117123 | Primary | Good | 20.6% | 202 |
| Hillmead Primary School117310 | Primary | Good | 20.1% | 223 |
| Highwood Primary School117089 | Primary | Good | 19.8% | 445 |
| Highover Junior Mixed and Infant School117115 | Primary | Outstanding | 5.8% | 433 |
| Highbury Infant School and Nursery117113 | Primary | Good | 9.3% | 195 |
| High Wych Church of England Primary School117398 | Primary | Good | 14.2% | 224 |
| High Leigh Primary School117270 | Primary | Requires Improvement | 37.0% | 166 |