| Thurstons Leisure Limited | Hospitality | 2010 |
| Thushimua Ltd | Other services | 2026 |
| TIA Lineker Limited | Administrative & support | 2019 |
| TIC Power Ltd | Construction | 2025 |
| Ticino B Limited | Real estate | 1992 |
| Ticket Market Limited | Information & communication | 2023 |
| Tide Trove Laundry Care Ltd | Other services | 2024 |
| Tidy Media Group Ltd | Financial services | 2018 |
| Tidy Productions Limited | Information & communication | 2009 |
| Tidytwo Ltd | Information & communication | 2026 |
| Tiewan Ltd | Wholesale & retail | 2026 |
| Tiftn Limited | Transport & logistics | 2020 |
| Tikari Limited | Professional & scientific | 2014 |
| Tilbury Express Limited | Transport & logistics | 2016 |
| Tilbury Nursery Ltd | Education | 2024 |
| Tile-Hub Limited | Construction | 2020 |
| Tiller & Sons Limited | Real estate | 2019 |
| Tilly Healthcare Ltd | Health & social care | 2023 |
| Tillytunes Limited | Administrative & support | 2009 |
| TIM 4 U Construction Limited | Construction | 2024 |
| TIM Wright Limited | Manufacturing | 2001 |
| Timall Construction Limited | Construction | 2024 |
| Timall Design & Build Ltd | Construction | 2020 |
| Timbermill Way Management Company Limited | Real estate | 2008 |
| Time CRE8IVE LLP | | 2010 |
| Time Management International Limited | Wholesale & retail | 2016 |
| Timefire Ltd | Information & communication | 2019 |
| Timeless Brands Ltd | Wholesale & retail | 2020 |
| Timeless IS Best Limited | Administrative & support | 2022 |
| Timeless.Shutter Ltd | Professional & scientific | 2025 |
| Timogel Limited | Information & communication | 2001 |
| Timothy Lord Limited | Professional & scientific | 2013 |
| Tims Media Productions Ltd | Wholesale & retail | 2020 |
| Tinarel Ltd | Professional & scientific | 2024 |
| Tindall Electrical Solutions Limited | Construction | 2018 |
| Tindall Group Limited | Professional & scientific | 2018 |
| Tiny Omega Ltd | Wholesale & retail | 2026 |
| Tiptop Properties Limited | Real estate | 2003 |
| Tirnanean Surveying & Estimating Limited | Construction | 2017 |
| Tismo Limited | Professional & scientific | 2011 |
| Title Sequence Ltd | Professional & scientific | 2023 |
| Tivon Fine Jewellery Limited | Manufacturing | 2022 |
| Tixrain Ltd | Administrative & support | 2024 |
| Tjane Consulting Ltd | Information & communication | 2013 |
| TJM Music Limited | Arts & recreation | 2014 |
| TJM Networks Limited | Information & communication | 2018 |
| TK Best Food & Wine Limited | Wholesale & retail | 2026 |
| TM2 Group Properties Ltd | Real estate | 2026 |
| Tmbooking Ltd | Other services | 2019 |
| Tmsf Properties Limited | Real estate | 2026 |
| TMW Consultancy Ltd | Professional & scientific | 2020 |
| TN Ahmed Limited | Health & social care | 2006 |
| TNB Building Ltd | Construction | 2022 |
| Tnrj Ltd | Information & communication | 2013 |
| TO BEE Group Ltd | Professional & scientific | 2020 |
| Toby Kelly Ltd | Construction | 2025 |
| Together MS Ltd | Professional & scientific | 2025 |
| Tokomed Ltd | Professional & scientific | 2020 |
| Tokyo AI Ltd | Information & communication | 2020 |
| Tokyo MIC Ltd | Transport & logistics | 2026 |
| Tolou Property Limited | Real estate | 2023 |
| TOM Building Ltd | Construction | 2024 |
| Tomboli Limited | Other services | 2019 |
| Tomski Limited | Financial services | 2013 |
| Tomy Advertising UK Limited | Professional & scientific | 2013 |
| TONI97 Limited | Water & waste | 2019 |
| Tony Levy Consultancy Ltd | Professional & scientific | 2011 |
| Tony Santos Tax Preparer Ltd | Professional & scientific | 2020 |
| Tooth Club Berkhamsted Limited | Health & social care | 2020 |
| Tooth Club Billericay Limited | Health & social care | 2022 |
| Tooth Club Bishops Stortford Limited | Health & social care | 2022 |
| Tooth Club BSE Limited | Health & social care | 2023 |
| Tooth Club Group Limited | Health & social care | 2022 |
| Tooth Club Guildford Limited | Health & social care | 2024 |
| Tooth Club Holding Limited | Financial services | 2022 |
| Tooth Club Ipswich Limited | Health & social care | 2020 |
| Tooth Club Loughton Limited | Health & social care | 2020 |
| Tooth Club OP Co Ltd | Health & social care | 2021 |
| Tooth Club Orpington Limited | Health & social care | 2024 |
| Tooth Club Romford Limited | Health & social care | 2022 |
| Tooth Club Southend Limited | Health & social care | 2020 |
| Tooth Club Stevenage Limited | Health & social care | 2020 |
| Tooth Club Tunbridge Wells Ltd | Health & social care | 2024 |
| Top Car Wash 01 Ltd | Administrative & support | 2025 |
| Top Global Quality Limited | Health & social care | 2009 |
| Top Glove (UK) Ltd. | Administrative & support | 2001 |
| Top Team Solutions Ltd | Construction | 2019 |
| Topdesk UK Limited | Information & communication | 2005 |
| Torch Outdoor Limited | Professional & scientific | 2011 |
| Torgold Limited | Construction | 2002 |
| Torkan Care Limited | Health & social care | 2022 |
| Torkan CIC | Health & social care | 2022 |
| Tormo Limited | Manufacturing | 1941 |
| Tornano Limited | Financial services | 2022 |
| Toroidz Ltd. | Wholesale & retail | 2017 |
| Tortuga Capital Limited | Real estate | 2021 |
| Total IT Management Limited | Wholesale & retail | 2010 |
| Total Mortgage Solutions Limited | Financial services | 2019 |
| Tots Hospitality Limited | Hospitality | 2025 |
| Tots Medicare Limited | Health & social care | 2022 |