| Sandringham School136609 | Secondary | Outstanding | 7.6% | 1,817 |
| Sandridge School117148 | Primary | Good | 22.5% | 142 |
| Sandon Junior Mixed and Infant School117147 | Primary | Requires Improvement | 22.2% | 27 |
| Samuel Ryder Academy138582 | All-through | Good | 18.5% | 1,577 |
| Samuel Lucas Junior Mixed and Infant School117337 | Primary | Outstanding | 5.3% | 419 |
| Saint Vincent de Paul Catholic Primary School151370 | Primary | Good | — | — |
| Saint Michael's Catholic High School137922 | Secondary | Good | 14.0% | 1,121 |
| Saint Joan of Arc Catholic School137914 | Secondary | Good | 8.4% | 1,199 |
| Saint Bernadette Voluntary Catholic Primary Academy150621 | Primary | Good | 12.8% | 212 |
| Saint Albert the Great Catholic Primary School, a Voluntary Academy149741 | Primary | Good | 11.2% | 205 |
| Saffron Green Primary School117195 | Primary | Good | 28.0% | 192 |
| Sacred Heart Catholic Primary School and Nursery117488 | Primary | Good | 5.8% | 351 |
| Sacred Heart Catholic Primary School148498 | Primary | Good | 8.3% | 193 |
| Rye Park Nursery School117072 | Nursery | Outstanding | 0.0% | 153 |
| Royal Masonic School for Girls117641 | Not applicable | — | — | 928 |
| Roundwood Primary School117211 | Primary | Good | 1.9% | 333 |
| Roundwood Park School136973 | Secondary | Outstanding | 7.4% | 1,437 |
| Round Diamond Primary School149206 | Primary | Outstanding | 8.4% | 453 |
| Roselands Primary School143409 | Primary | Good | 17.1% | 298 |
| Roman Way Academy147008 | Primary | Good | 22.4% | 234 |
| Roman Fields Academy148363 | Not applicable | Outstanding | 14.0% | 49 |
| Roger de Clare First CofE School117406 | Primary | Good | 13.1% | 235 |
| Roebuck Academy144419 | Primary | Good | 22.9% | 452 |
| Robert Barclay Academy143131 | Secondary | Good | 22.8% | 792 |
| Rivers Education Support Centre135890 | Not applicable | Good | 69.0% | 29 |
| Ridgeway Academy146305 | Secondary | Good | 31.7% | 929 |
| Rickmansworth School136606 | Secondary | Outstanding | 6.0% | 1,550 |
| Rickmansworth Park Junior Mixed and Infant School117304 | Primary | Outstanding | 6.1% | 197 |
| Richard Whittington Primary School151078 | Primary | Good | 15.6% | 288 |
| Richard Hale School139873 | Secondary | Good | 9.2% | 1,209 |
| Rhodes Wood Hospital School144726 | Not applicable | — | — | 34 |
| Reedings Junior School117280 | Primary | Good | 7.3% | 245 |
| Reed First School117129 | Primary | Good | 6.7% | 68 |
| Redbourn Primary School117236 | Primary | Good | 14.5% | 394 |
| Redbourn Park School148472 | Not applicable | — | — | 23 |
| Ralph Sadleir School140249 | Middle deemed secondary | Requires Improvement | 15.3% | 275 |
| Radlett Preparatory School Ltd117615 | Not applicable | — | — | 266 |
| Radlett Lodge School117646 | Not applicable | — | — | 55 |
| Queenswood School117609 | Not applicable | — | — | 463 |
| Queens' School136877 | Secondary | Outstanding | 10.3% | 1,660 |
| Purwell Primary School117224 | Primary | Good | 34.2% | 163 |
| Puller Memorial, Church of England, Voluntary Aided Primary School117453 | Primary | Good | 20.0% | 55 |
| Priors Wood Primary School117271 | Primary | Good | 16.9% | 222 |
| Preston Primary School117403 | Primary | Good | 2.9% | 68 |
| Presdales School137985 | Secondary | Outstanding | 9.0% | 1,166 |
| Prae Wood Primary School117315 | Primary | Good | 3.2% | 448 |
| Potten End CofE Primary School117414 | Primary | Good | 15.2% | 204 |
| Pope Paul Catholic Primary School151984 | Primary | Good | — | — |
| Ponsbourne St Mary's Church of England Primary School117396 | Primary | Good | 6.5% | 112 |
| Pixmore Junior School117259 | Primary | Good | 30.4% | 240 |