| Purwell Primary School117224 | Primary | Good | 28.3% | 129 |
| Queens' School136877 | Secondary | Outstanding | 10.5% | 1,697 |
| Queenswood School117609 | Not applicable | — | — | 426 |
| Radlett Lodge School117646 | Not applicable | — | — | 54 |
| Radlett Preparatory School Ltd117615 | Not applicable | — | — | 250 |
| Ralph Sadleir School140249 | Middle deemed secondary | Requires Improvement | 17.0% | 283 |
| Redbourn Park School148472 | Not applicable | — | — | 25 |
| Redbourn Primary School117236 | Primary | Good | 14.2% | 375 |
| Reed First School117129 | Primary | Good | 6.9% | 64 |
| Reedings Junior School117280 | Primary | Good | 7.4% | 243 |
| Rhodes Wood Hospital School144726 | Not applicable | — | — | 35 |
| Richard Hale School139873 | Secondary | Good | 9.8% | 1,207 |
| Richard Whittington Primary School151078 | Primary | Good | 15.3% | 273 |
| Rickmansworth Park Junior Mixed and Infant School117304 | Primary | Outstanding | 6.0% | 201 |
| Rickmansworth School136606 | Secondary | Outstanding | 6.0% | 1,575 |
| Ridgeway Academy146305 | Secondary | Good | 33.5% | 875 |
| Rivers Education Support Centre135890 | Not applicable | Good | 73.3% | 15 |
| Robert Barclay Academy143131 | Secondary | Good | 22.6% | 821 |
| Roebuck Academy144419 | Primary | Expected standard | 20.2% | 452 |
| Roger de Clare First CofE School117406 | Primary | Good | 12.9% | 211 |
| Roman Fields Academy148363 | Not applicable | Outstanding | 10.9% | 49 |
| Roman Way Academy147008 | Primary | Good | 18.9% | 219 |
| Roselands Primary School143409 | Primary | Good | 16.3% | 300 |
| Round Diamond Primary School149206 | Primary | Outstanding | 5.3% | 436 |
| Roundwood Park School136973 | Secondary | Outstanding | 7.6% | 1,421 |
| Roundwood Primary School117211 | Primary | Expected standard | 2.7% | 338 |
| Royal Masonic School for Girls117641 | Not applicable | — | — | 880 |
| Rye Park Nursery School117072 | Nursery | Outstanding | 0.0% | 147 |
| Sacred Heart Catholic Primary School148498 | Primary | Good | 8.4% | 202 |
| Sacred Heart Catholic Primary School and Nursery117488 | Primary | Good | 5.4% | 346 |
| Saffron Green Primary School117195 | Primary | Good | 35.0% | 177 |
| Saint Albert the Great Catholic Primary School, a Voluntary Academy149741 | Primary | Good | 11.8% | 204 |
| Saint Bernadette Voluntary Catholic Primary Academy150621 | Primary | Good | 11.8% | 206 |
| Saint Joan of Arc Catholic School137914 | Secondary | Good | 11.3% | 1,198 |
| Saint Michael's Catholic High School137922 | Secondary | Good | 14.2% | 1,130 |
| Saint Vincent de Paul Catholic Primary School151370 | Primary | Good | 8.5% | 433 |
| Samuel Lucas Junior Mixed and Infant School117337 | Primary | Outstanding | 5.5% | 416 |
| Samuel Ryder Academy138582 | All-through | Good | 19.8% | 1,577 |
| Sandon Junior Mixed and Infant School117147 | Primary | Needs attention | 27.3% | 22 |
| Sandridge School117148 | Primary | Good | 24.6% | 130 |
| Sandringham School136609 | Secondary | Outstanding | 7.5% | 1,777 |
| Sarratt Church of England Primary School146723 | Primary | Good | 8.6% | 163 |
| Sauncey Wood Primary School117102 | Primary | Good | 22.4% | 147 |
| Shenley Primary School117150 | Primary | Good | 38.8% | 119 |
| Shephalbury Park Primary School135084 | Primary | Good | 24.0% | 228 |
| Shepherd Primary117096 | Primary | Good | 21.7% | 179 |
| Sheredes Primary School117353 | Primary | Outstanding | 6.2% | 456 |
| Sherrardswood School117622 | Not applicable | — | — | 445 |
| Simon Balle All-Through School140294 | All-through | Outstanding | 9.8% | 1,617 |
| Sir John Lawes School137270 | Secondary | Outstanding | 9.7% | 1,373 |