| Radlett Grill Ltd | Hospitality | 2025 |
| Radlett Launderette & Alterations Limited | Other services | 2022 |
| Radlett Medical Aesthetics Ltd | Other services | 2025 |
| Radlett Opticians Ltd | Wholesale & retail | 2004 |
| Radlett Radio Cars Group Ltd | Transport & logistics | 2019 |
| Radlett Reform Synagogue | Other services | 2014 |
| Radlett Tech Ltd | Other services | 2022 |
| Raga Services 2025 Limited | Wholesale & retail | 2025 |
| Raico London Ltd | Wholesale & retail | 2019 |
| Ramosy Electrical Ltd | Construction | 2026 |
| Ramstrack Ltd | Wholesale & retail | 2025 |
| Rapsim Limited | Education | 2007 |
| RAS Property Limited | Real estate | 2015 |
| RBR Film and TV Ltd | Construction | 2023 |
| Rd&L Legal Services and Investments Limited | Real estate | 2016 |
| Realfit Active Ltd | Wholesale & retail | 2026 |
| Red Door Holding Limited | Real estate | 2025 |
| Red Dust Properties Limited | Real estate | 2018 |
| Red Lion PMC Limited | Professional & scientific | 2025 |
| Red Sphere Challenge Ltd | Professional & scientific | 2024 |
| Redington Gardens Limited | Real estate | 2014 |
| Redshort Property Investments LLP | | 2024 |
| Regain - the Charity for Tetraplegics | Administrative & support | 1993 |
| Regalsteer Limited | Transport & logistics | 2020 |
| Regent Office Cleaning Co. Limited | Other services | 1963 |
| Rehubs Healthcare UK Limited | Health & social care | 2023 |
| Reid Integration Services Limited | Information & communication | 2023 |
| Remark Consulting Ltd. | Professional & scientific | 2020 |
| Renaissance Property Holdings Limited | Real estate | 2019 |
| Rent 24 LLP | | 2005 |
| Rentals 24H Limited | Real estate | 2001 |
| Reputation Building Limited | Construction | 2017 |
| Resolve Care Limited | Other services | 2012 |
| Resolve Supported Housing Ltd | Health & social care | 2022 |
| Resonate Films Ltd | Information & communication | 2009 |
| Rest Harrow Management Company Limited | Households | 2019 |
| RG3 Limited | Real estate | 2026 |
| Rgje Media Limited | Information & communication | 2026 |
| Riccads Limited | Real estate | 2020 |
| Richard Vandekar Limited | Wholesale & retail | 1992 |
| Ridge Hill (Shenley) Management Company Limited | Households | 2021 |
| Rise Therapeutic & Executive Coaching Ltd | Professional & scientific | 2024 |
| Ritzy RU Limited | Wholesale & retail | 2025 |
| Rivalvalue Property Management Limited | Administrative & support | 1992 |
| Rlst Ltd | Real estate | 2022 |
| Road Tech Trustees Limited | Extraterritorial | 2018 |
| Robertson Partnership Ltd | Professional & scientific | 2022 |
| Rocald Ltd | Construction | 2011 |
| Rocco Property Solutions Ltd | Real estate | 2025 |
| Roche Wetherall Limited | Other services | 2018 |
| Rosanna Lynch Ltd | Health & social care | 2025 |
| Roselux Travel Ltd | Transport & logistics | 2025 |
| Rosemax Investments Limited | Real estate | 2013 |
| Rosemont Services International Ltd | Transport & logistics | 2026 |
| Roundturn Insights & Advisory Ltd | Professional & scientific | 2023 |
| Roverley Limited | Real estate | 1993 |
| RR Scenery Ltd | Information & communication | 2022 |
| RS Stone Limited | Financial services | 2014 |
| RSS Fashions Limited | Wholesale & retail | 2002 |
| Rubble Mania Limited | Information & communication | 2024 |
| Rumbros Ltd | Arts & recreation | 2018 |
| Rupsoft Ltd | Information & communication | 2021 |
| RWB Finance Consulting Ltd | Professional & scientific | 2014 |
| Rydal Close (Freehold) Limited | Real estate | 1993 |
| Rydal Close Property Management Co. Limited | Real estate | 1960 |
| Rydon Ltd | Wholesale & retail | 2025 |
| S & B Independent Limited | Administrative & support | 2000 |
| S Clarke Investments Ltd | Real estate | 2024 |
| S G Cardiac Research Limited | Professional & scientific | 2012 |
| S G Textiles Ltd | Wholesale & retail | 2016 |
| S.E.Y. Properties Limited | Real estate | 2019 |
| S9 KHK LLP | | 2022 |
| Safe Choice Roofing & Guttering Ltd | Construction | 2026 |
| SAI Shraddha Investment Ltd | Real estate | 2020 |
| Saigal Properties Limited | Construction | 1973 |
| Sallaghan Consulting Limited | Professional & scientific | 2026 |
| Salsola London Ltd | Wholesale & retail | 2026 |
| Salt AV Ltd | Construction | 2024 |
| Salt Salon (Borough) Limited | Other services | 2025 |
| Salt Salon Limited | Other services | 2020 |
| SAM Neal Metalworks Limited | Construction | 2014 |
| Samaa Investment Limited | Real estate | 2015 |
| Samella Limited | Professional & scientific | 2023 |
| Samtach Services Ltd | Arts & recreation | 2025 |
| Samuelson Media Limited | Information & communication | 2012 |
| Sanctex Ltd | Wholesale & retail | 2002 |
| Sandalex Limited | Construction | 1962 |
| Sands Financial Ltd | Professional & scientific | 2023 |
| Sara Hausmann Limited | Health & social care | 2021 |
| Sarana Advisory Ltd | Information & communication | 2026 |
| Sari Jules Shop Ltd | Wholesale & retail | 2014 |
| Sass Trading Ltd | Professional & scientific | 2019 |
| SCENT2MARKET UK Ltd | Manufacturing | 2010 |
| Scjp Quantity Surveying Limited | Professional & scientific | 2010 |
| Scleaningservices Ltd | Administrative & support | 2026 |
| Scotscraig Properties Limited | Real estate | 2010 |
| Sduk Limited | Professional & scientific | 2019 |
| Seafarer Sailing Limited | Administrative & support | 2011 |
| Search Hero Ltd | Administrative & support | 2019 |
| Secret Travel Club Ltd | Administrative & support | 2024 |