| TJF Surfacing Ltd | Construction | 2025 |
| TJK Business Services Limited | Information & communication | 2014 |
| TJL Enterprise Ltd | Financial services | 2021 |
| TJL Property Lettings Ltd | Real estate | 2023 |
| TJR Electricals(Swindon) Ltd | Construction | 2017 |
| TKT Transport Services Ltd | Transport & logistics | 2013 |
| TL Donnellon Ltd | Construction | 2016 |
| TLL Wickford LLP | | 2023 |
| TLN Marketing Limited | Administrative & support | 2023 |
| TLP Carpentry Ltd | Manufacturing | 2024 |
| TM Adele Cares Limited | Health & social care | 2018 |
| TM Engineers Limited | Manufacturing | 2011 |
| TM Group (UK) Limited | Information & communication | 2004 |
| TM Kitchens and Joinery Limited | Manufacturing | 2008 |
| TM Motor Services Limited | Manufacturing | 2015 |
| TM Properties (Swindon) Ltd | Real estate | 2023 |
| TM Property Searches Limited | Information & communication | 1999 |
| TM Search Choice Limited | Information & communication | 2004 |
| TM Ventures Limited | Information & communication | 2004 |
| TMA Technology Ltd | Information & communication | 2013 |
| TMB Property Empire Ltd | Real estate | 2021 |
| TME Transport Limited | Transport & logistics | 2015 |
| TMG Jewellery Ltd | Manufacturing | 2025 |
| TMG Services Group Limited | Health & social care | 2016 |
| TN78 Ltd | Other services | 2019 |
| TNM Drylining Limited | Construction | 2021 |
| TNT Consulting Worldwide Ltd | Information & communication | 2016 |
| TO BE Continued Clothing Ltd | Wholesale & retail | 2021 |
| TO ME to YOU Services Ltd | Transport & logistics | 2025 |
| Tobi Accounting Services Limited | Professional & scientific | 2024 |
| Toby's Field Property Company Limited | Real estate | 2011 |
| Todah Care Ltd | Health & social care | 2020 |
| Todoforyou Limited | Extraterritorial | 2018 |
| Togoman Export Import Ltd | Wholesale & retail | 2017 |
| Tokipaw Limited | Wholesale & retail | 2025 |
| Toll House (Lyneham) Management Company Limited | Households | 2018 |
| TOM G Group Ltd | Construction | 2020 |
| TOM Gallagher Group Limited | Wholesale & retail | 2001 |
| TOM Gallagher Van Centre Limited | Wholesale & retail | 2001 |
| TOM Transport Ltd | Extraterritorial | 2011 |
| Tom's Bakehouse Limited | Manufacturing | 2024 |
| Tom's Car Wash Ltd | Other services | 2017 |
| Tom's Truck Limited | Transport & logistics | 2014 |
| Tomas Carpentry Ltd | Construction | 2025 |
| Tomasz Duranski Ltd | Construction | 2019 |
| Tomasz Kempa Limited | Transport & logistics | 2015 |
| Tombere Ltd | Information & communication | 2021 |
| Tomlin Scaffolding Limited | Wholesale & retail | 1994 |
| Tomtitours Limited | Administrative & support | 2023 |
| Tone Gibbs Props Ltd | Information & communication | 2011 |
| Toni Roofing Ltd | Construction | 2023 |
| Toni's Garage Ltd | Wholesale & retail | 2019 |
| Tonic Construction Limited | Construction | 1999 |
| Tonic Trustees Limited | Administrative & support | 2019 |
| Toninka Ltd | Wholesale & retail | 2024 |
| Tony Valentine Golf Centre Limited | Administrative & support | 2004 |
| Toolcraft Plastics (Swindon) Limited | Manufacturing | 1982 |
| Toomey Safety Services Ltd | Professional & scientific | 2024 |
| Toothstories Limited | Health & social care | 2024 |
| Top Bags Limited | Wholesale & retail | 1997 |
| Top Building Solutions Ltd | Construction | 2023 |
| Top Coat Decorators Ltd | Construction | 2022 |
| Top CUT Barber Faringdon Ltd | Other services | 2024 |
| Top END Trade Limited | Real estate | 2022 |
| Top Flite Scaffolding Limited | Construction | 2001 |
| Top K Ltd | Wholesale & retail | 2019 |
| Top Marks Driving Consultancy Limited | Education | 2008 |
| Top Print Swindon Ltd | Manufacturing | 2022 |
| Top Professionals Access Limited | Education | 2019 |
| Top Star (UK) Limited | Wholesale & retail | 2004 |
| Top Tech Consulting Ltd | Professional & scientific | 2021 |
| Topaz Talent Limited | Professional & scientific | 2018 |
| Topcutgames Ltd | Wholesale & retail | 2024 |
| Topfry Swindon Ltd | Hospitality | 2026 |
| Topland Construction Ltd | Construction | 2017 |
| Topp Rank Services Limited | Administrative & support | 2018 |
| Toptoes Podiatry Limited | Health & social care | 2016 |
| Toropurgn Delivery Ltd | Transport & logistics | 2019 |
| Torque Events Limited | Administrative & support | 2020 |
| Torus Recruitment Solutions Limited | Professional & scientific | 2025 |
| Tosesoft Ltd | Information & communication | 2025 |
| Total Build & Landscape Ltd | Construction | 2026 |
| Total Cladding and Roofing Ltd | Construction | 2021 |
| Total Clearance Swindon Ltd | Water & waste | 2025 |
| Total Construct Ltd | Construction | 2025 |
| Total Contractor Group Ltd | Financial services | 2025 |
| Total Delivery Cosmetics Ltd | Information & communication | 2026 |
| Total Delivery MED TEC Ltd | Wholesale & retail | 2026 |
| Total Delivery Pharma Manufacturing Ltd | Wholesale & retail | 2026 |
| Total Delivery Pharma Services Ltd | Administrative & support | 2023 |
| Total Delivery Recruitment Services Ltd | Administrative & support | 2026 |
| Total Fitness World Limited | Wholesale & retail | 2021 |
| Total Guide to Ltd | Administrative & support | 2011 |
| Total Heating & Cooling Services Ltd | Construction | 2022 |
| Total Heating & Plumbing Services Ltd | Administrative & support | 2006 |
| Total Lane Ltd | Construction | 2026 |
| Total Marketing SOL. Limited | Transport & logistics | 2015 |
| Total Martial Arts Premier Academy LLP | | 2020 |
| Total Safety First Limited | Information & communication | 2013 |
| Total Service Management Ltd | Construction | 2017 |