| Susat Consultancy Limited | Administrative & support | 2015 |
| Sustainable Construction Solutions Limited | Professional & scientific | 2014 |
| Sustainable Value Creation Limited | Professional & scientific | 2008 |
| Suziekad Ltd | Health & social care | 2024 |
| Svarg Limited | Wholesale & retail | 2019 |
| SW Flowers London Limited | Wholesale & retail | 2018 |
| SW5 Limited | Wholesale & retail | 2021 |
| Swakeleys Acquisitions Ltd | Real estate | 2023 |
| Swakeleys Associates Limited | Financial services | 2001 |
| Swakeleys Digital Services Ltd | Manufacturing | 2017 |
| Swakeleys Estates Limited | Real estate | 2023 |
| Swakeleys School for Girls | Education | 2011 |
| Swallow Glazing Limited | Administrative & support | 2014 |
| Swallow House Estates Limited | Real estate | 1986 |
| Swan Court Right to Manage Company Limited | Professional & scientific | 2008 |
| Swan Fashion Ltd | Wholesale & retail | 2023 |
| Swaneil Ltd | Hospitality | 2024 |
| Swaran UK Ltd | Other services | 2019 |
| Swash Holdings Ltd | Information & communication | 2021 |
| Sweet Flour Limited | Hospitality | 2019 |
| Sweet Lemon Uxbridge Ltd | Hospitality | 2026 |
| Sweet Stuff Ltd | Hospitality | 2022 |
| Sweethaus Ltd | Wholesale & retail | 2025 |
| Swelter Productions Ltd | Wholesale & retail | 2021 |
| Swift & Co Investments Limited | Financial services | 2025 |
| Swift Courtesy Cars UK Ltd | Wholesale & retail | 2017 |
| Swift Hive Ltd | Wholesale & retail | 2026 |
| Swift Xport Ltd | Wholesale & retail | 2024 |
| Swiftlineone Ltd | Construction | 2019 |
| Swiftlybird Couriers Ltd | Transport & logistics | 2024 |
| Swordfish UK Limited | Wholesale & retail | 2004 |
| SY LAU Biology & Science Tutoring Ltd | Education | 2022 |
| Sykander Tech Limited | Administrative & support | 2025 |
| Sylvese Limited | Professional & scientific | 2025 |
| Symbiosis IT Solutions Ltd | Information & communication | 2011 |
| Symfony Homes Ltd | Real estate | 2019 |
| Symphony Healthcare Ltd | Health & social care | 2014 |
| Syna Ventures Ltd | Wholesale & retail | 2025 |
| Synerj International Ltd | Information & communication | 2021 |
| Synsolve Limited | Information & communication | 2025 |
| Sypd Ltd | Arts & recreation | 2026 |
| SZ International Limited | Professional & scientific | 2025 |
| T & a Builders Limited | Construction | 2001 |
| T & a Installations Services Limited | Construction | 2017 |
| T & D Bicester HCW Ltd | Other services | 2019 |
| T & D Bicester Tyres Ltd | Other services | 2019 |
| T & J Investments Limited | Real estate | 2018 |
| T J Charles Estates Ltd. | Hospitality | 2021 |
| T Kelly Limited | Real estate | 2025 |
| T Moroney Services Limited | Construction | 2020 |
| T P & N Electrical Contractors Limited | Construction | 2000 |
| T P and N Holdings Limited | Financial services | 2015 |
| T Pro Build-Design Limited | Construction | 2016 |
| T Stamp Limited | Construction | 2013 |
| T&N Oven Cleaning Company Limited | Administrative & support | 2022 |
| T'S Hair Care Limited | Other services | 2013 |
| T.Designstudio Ltd | Professional & scientific | 2024 |
| T.R. Ward Brokerage Ltd | Financial services | 2018 |
| T.S.L. Finance Limited | Wholesale & retail | 2000 |
| T1 Real Estates Limited | Real estate | 2020 |
| T28 Learners Limited | Education | 2023 |
| T4 Uxbridge Ltd | Wholesale & retail | 2021 |
| TA Enterprises Ltd | Wholesale & retail | 2025 |
| TAA Shopfitters & Refrigeration Limited | Professional & scientific | 2017 |
| Taaf Limited | Professional & scientific | 2013 |
| TAB Carpet & Flooring Ltd | Construction | 2024 |
| TAB Projects Limited | Other services | 2021 |
| Taco Mondo Ltd | Hospitality | 2015 |
| Tacos Flackos Ltd | Hospitality | 2023 |
| Taeps Limited | Administrative & support | 2021 |
| TAG CAP Ltd | Wholesale & retail | 2023 |
| Tagg Art Scenery Limited | Arts & recreation | 2016 |
| TAI Serrennog Ltd | Hospitality | 2024 |
| Tailor & Build Ltd | Construction | 2019 |
| Tailor Consultant Solutions Ltd | Information & communication | 2025 |
| Taimoor Hussain Limited | Information & communication | 2025 |
| Taisa & Lavon Property Holdings Ltd. | Real estate | 2021 |
| Taiyochan Corporation Ltd | Professional & scientific | 2019 |
| TAJ Developers Ltd | Construction | 2022 |
| Takal Consultancy Ltd | Administrative & support | 2017 |
| Takhar Group Ltd | Wholesale & retail | 2025 |
| Talent Acquisition and Retention Partners Limited | Administrative & support | 2012 |
| Talent Play Limited | Wholesale & retail | 2019 |
| Talent Transformation Limited | Administrative & support | 2021 |
| Talukder Properties Ltd | Real estate | 2022 |
| TAM Events & Cafe Ltd | Hospitality | 2018 |
| Tamana Ltd | Wholesale & retail | 2019 |
| Tamarin Ventures Limited | Wholesale & retail | 2020 |
| Tamaro Services Ltd | Transport & logistics | 2019 |
| Tammy Five Star Property Ltd | Real estate | 2023 |
| Tamo Limited | Wholesale & retail | 1958 |
| Tamt Consulting Ltd | Administrative & support | 2011 |
| TAN Supplies Ltd | Wholesale & retail | 2025 |
| Taneja Clinical and Teaching Services Limited | Education | 2008 |
| Taneja Limited | Other services | 2025 |
| Tangledene Properties Ltd | Real estate | 2024 |
| Tanishq Logistics Ltd | Transport & logistics | 2014 |
| Tantarra Management Company Limited | Households | 2006 |
| Tanti Facilities Maagement Limited | Administrative & support | 2026 |
| Taparia Consultants Ltd | Professional & scientific | 2011 |