| Tonic TLC Limited | Health & social care | 2021 |
| Tony K Ltd | Construction | 2013 |
| Tony Mcfadden Developments Limited | Construction | 1992 |
| Tony Nerses Ltd | Agriculture & fishing | 2015 |
| Tony Quality Services Ltd | Administrative & support | 2025 |
| Tony's Catering Services Limited | Hospitality | 2024 |
| Tonyx Management Limited | Real estate | 2012 |
| Toomi Properties Ltd | Real estate | 2022 |
| Toopchian Construction Ltd | Construction | 2024 |
| Toops Limited | Wholesale & retail | 2010 |
| Tooth Dynamix Ltd | Health & social care | 2014 |
| Tooth Logic Limited | Health & social care | 2014 |
| Toothaid Ltd | Other services | 2022 |
| Top Advisor Limited | Information & communication | 2014 |
| Top Cars London Ltd | Wholesale & retail | 2024 |
| Top Class One (UK) Limited | Professional & scientific | 2025 |
| Top CUT Grooming Ltd | Other services | 2024 |
| Top House Contractors Limited | Construction | 2008 |
| Top One Class Limited | Professional & scientific | 2012 |
| Top Phone International Limited | Wholesale & retail | 2023 |
| Top Products Ltd | Wholesale & retail | 2025 |
| Top Reach Properties Limited | Real estate | 2019 |
| Top VAS Construct Ltd | Construction | 2024 |
| Topawo Limited | Other services | 2024 |
| TOPAZ15 Limited | Professional & scientific | 2022 |
| Topdeal Online Ltd | Wholesale & retail | 2025 |
| Topdealshopping Ltd | Wholesale & retail | 2018 |
| Topic Records Limited | Information & communication | 1958 |
| Topliner Management Limited | Professional & scientific | 2001 |
| Topnotch Sushi Ltd | Hospitality | 2024 |
| Toposophy Limited | Professional & scientific | 2017 |
| Topper Consultancy Limited | Health & social care | 2016 |
| Tops Hub Limited | Hospitality | 2025 |
| Tops Pizza (Rayners Lane) Limited | Hospitality | 2023 |
| Tops Pizza (Wandsworth) Ltd | Hospitality | 2025 |
| Tops Pizza Enfield Ltd | Hospitality | 2025 |
| Tops Pizza in Ware Ltd | Hospitality | 2025 |
| Tops Pizza S015 Ltd | Hospitality | 2026 |
| Tops Pizza S018 Ltd | Hospitality | 2026 |
| Tops Pizza South Ltd | Hospitality | 2025 |
| Tops Tasty Slice Ltd | Hospitality | 2025 |
| Topsik Limited | Administrative & support | 2012 |
| Topuzi Steel Fixers Ltd | Administrative & support | 2019 |
| Torro Capital Limited | Administrative & support | 2017 |
| Torstead Limited | Real estate | 1962 |
| TOS Trans Ltd | Construction | 2014 |
| Tosyns Limited | Construction | 2011 |
| Total Estate Maintenance Ltd | Construction | 2013 |
| Totalcare Homes Ltd | Construction | 2025 |
| Totally Aluminum Windows Ltd | Manufacturing | 2020 |
| Toti Alliance LLP | | 2023 |
| Touch a Sky Ltd | Wholesale & retail | 2023 |
| Touch and Glow Beauty Clinic Ltd | Other services | 2018 |
| Touchfirst Limited | Real estate | 1994 |
| Touchfirst SPV Limited | Real estate | 2019 |
| Tours in a Taxi (London) Limited | Administrative & support | 2025 |
| TOW R US Ltd | Wholesale & retail | 2024 |
| Towards AGI Ventures Limited | Professional & scientific | 2025 |
| Towcester Smiles Limited | Health & social care | 2026 |
| Tower House Investments Ltd | Real estate | 1998 |
| Tower Residential Investments Limited | Real estate | 2010 |
| Tower Toys Limited | Real estate | 1956 |
| Towercross Properties Limited | Extraterritorial | 2003 |
| Townley Gardens Limited | Administrative & support | 2019 |
| Towtech Solutions Ltd | Transport & logistics | 2025 |
| Toynbee Clarke (Interiors) Limited | Wholesale & retail | 1961 |
| TP London Construction Ltd | Construction | 2025 |
| TPM Interiors Limited | Construction | 2021 |
| TPS (London) Limited | Real estate | 2015 |
| Tpseal Limited | Professional & scientific | 2008 |
| TR Dental Ltd | Health & social care | 2021 |
| TR Finance Limited | Financial services | 2011 |
| Tracy Lewis's Childcare Limited | Health & social care | 2010 |
| Trade City Centre Ltd | Other services | 2017 |
| Trade Secrets Communications Limited | Professional & scientific | 2005 |
| Trade to AID Limited | Administrative & support | 2017 |
| Trade to AID Sport Ltd | Administrative & support | 2017 |
| Tradebest Ltd | Wholesale & retail | 2018 |
| Tradeboost AI Ltd | Information & communication | 2026 |
| Tradelink (London) Limited | Wholesale & retail | 1986 |
| Trademind Retail Ltd | Wholesale & retail | 2025 |
| Traderouteuk Ltd | Wholesale & retail | 2025 |
| Traditional Irish Food Company Ltd | Wholesale & retail | 2004 |
| Traian Services Ltd | Construction | 2019 |
| Trailtale Services C.I.C. | Other services | 2023 |
| Tramkon Limited | Professional & scientific | 2025 |
| Tranby Mews Freehold Limited | Households | 2022 |
| Trans George Ltd | Transport & logistics | 2026 |
| Transcargo Logistics Ltd | Transport & logistics | 2025 |
| Transfood International Ltd | Wholesale & retail | 2017 |
| Transhair & Aesthetic Team Limited | Other services | 2013 |
| Transmodal Logistics International (UK) Ltd | Transport & logistics | 2007 |
| Transport Domain Control (TDC) Ltd. | Information & communication | 2017 |
| Transport in London Limited | Transport & logistics | 2025 |
| Transporty Limited | Transport & logistics | 2024 |
| Tratoria Lounge Ltd | Hospitality | 2025 |
| Travaille Limited | Real estate | 2022 |
| Travel Club Limited | Administrative & support | 2023 |
| Travel Gennie Ltd | Administrative & support | 2022 |
| Trawlers Fish Bar Limited | Hospitality | 2013 |