| Sunrise Printers and Publishers Limited | | 1975 |
| Sunrise Shopfitters Ltd. | | 1991 |
| Sunshine Gardens Limited | Real estate | 2015 |
| Super Image Limited | Information & communication | 1996 |
| Supergames Limited | Arts & recreation | 1976 |
| Superlative Computing Ltd | Information & communication | 1997 |
| Supreme Team Ltd | Professional & scientific | 2003 |
| Surelock International Ltd | Administrative & support | 2001 |
| Surematters Ltd | Information & communication | 1999 |
| Surequote Limited | Wholesale & retail | 1995 |
| Surface Measurement Systems Limited | Manufacturing | 1989 |
| Surge Accountancy Limited | Professional & scientific | 2020 |
| Surgical Dermatology Ltd. | Health & social care | 2026 |
| Surrey Hills Grab Service Ltd | Water & waste | 2002 |
| Survey Design (Harrow) Limited | Professional & scientific | 2005 |
| Suzanne's Dance Supplies Limited | Wholesale & retail | 1998 |
| Swancourt (Ruislip) Management Company Limited | Households | 1991 |
| Sweet Anjana Bhog UK Ltd | Manufacturing | 2025 |
| Sweet Indulgence Ltd | Wholesale & retail | 2018 |
| Sweetcroft Limited | Wholesale & retail | 1972 |
| Swift AA Investments Ltd | Real estate | 2024 |
| Swinbrook Limited | Professional & scientific | 1993 |
| Swordmaster Limited | Arts & recreation | 2005 |
| Syhana Opticians Limited | Professional & scientific | 2016 |
| Syndrig Limited | Information & communication | 2006 |
| SYNTILL8 Limited | Professional & scientific | 1997 |
| Sysright Limited | Information & communication | 2002 |
| Syssoft Consulting Limited | Information & communication | 1999 |
| Systemology UK Limited | Professional & scientific | 2003 |
| Systems Hub Ltd | Information & communication | 2017 |
| T & K Bryant Limited | Construction | 1986 |
| T & S Knight Limited | Health & social care | 2004 |
| T C Computer Consultants Limited | Professional & scientific | 1995 |
| T O'Neill (Civil Engineering) Limited | Construction | 2013 |
| T R Harris Ltd | Professional & scientific | 2007 |
| T.G.S. Leadwork & Roofing Limited | Construction | 2006 |
| T.H.A. South & SON Limited | Real estate | 1975 |
| T.L.C Motors Ltd | Wholesale & retail | 2023 |
| Tabgold Limited | Administrative & support | 2006 |
| TAG Transfers Limited | Transport & logistics | 2002 |
| Tahra Zafar Ltd | Arts & recreation | 2018 |
| Talboys (Builders) Limited | Real estate | 1951 |
| Talking Pictures (UK) Limited | Information & communication | 2005 |
| Tanavneet Limited | Real estate | 2015 |
| Tanner GAS Services Ltd | Construction | 2004 |
| Tarak Trade Ltd | Wholesale & retail | 2025 |
| Tarapore Consultancy Limited | Professional & scientific | 1990 |
| Taras Gas/Elec Ltd | Construction | 2019 |
| Target Traders Limited | Wholesale & retail | 1994 |
| Tari Digital Limited | Information & communication | 1997 |
| Tariq Halal Meat (UK) Ltd | Wholesale & retail | 2004 |
| Tariq Halal Meat Limited | Wholesale & retail | 1996 |
| TAS Consulting Limited | Information & communication | 2005 |
| Tashglen Limited | Other services | 1972 |
| Tastemore Limited | Hospitality | 2001 |
| Tatman Limited | Information & communication | 1998 |
| Taxcompiler Limited | Information & communication | 2013 |
| Taxmech Consultants Ltd | Information & communication | 2023 |
| Taxtone Limited | Real estate | 1976 |
| Taxwallah Limited | Professional & scientific | 2007 |
| Taylor Woodrow Services Limited | Professional & scientific | 1957 |
| TDS Holdings (Staines) Limited | Real estate | 2015 |
| Teamwork Construction Limited | Construction | 1997 |
| Teamwork Limited | Information & communication | 2000 |
| Teare Medical Limited | Health & social care | 2010 |
| Tearfund | Health & social care | 1970 |
| Tearfund Trading Limited | Extraterritorial | 1999 |
| Tech MD Ltd | Wholesale & retail | 2018 |
| Technica Services LLP | | 2018 |
| Technical & Management Consultancy Limited | Extraterritorial | 2005 |
| Technical Service Systems Limited | Transport & logistics | 1998 |
| Technokraft Limited | Wholesale & retail | 2016 |
| Technology Appraisals Limited | Information & communication | 1984 |
| Technology Implementation Services Limited | Information & communication | 2006 |
| Technology Support Consultancy Limited | Information & communication | 2003 |
| Technoplan Limited | Professional & scientific | 2003 |
| Tecnostar Limited | Real estate | 1984 |
| Tecon Limited | Extraterritorial | 1995 |
| Tecvale Consultants Limited | Administrative & support | 2005 |
| Teddington Park Place Limited | Households | 2000 |
| Tee-Jay Precision Engineering Limited | Other services | 2000 |
| Teeth and Smiles Ltd | Health & social care | 2010 |
| Teignmouth Gardens Properties Limited | Real estate | 2021 |
| TEJ & Co UK Limited | Professional & scientific | 2004 |
| Teknite Limited | Other services | 2001 |
| Telcotec Ltd | Information & communication | 2004 |
| Telecomhelp Ltd | Information & communication | 2008 |
| Tell the Story Films Ltd | Information & communication | 2022 |
| Tembe DIY Products Limited | Wholesale & retail | 2004 |
| Temperance Seven Limited(The) | Administrative & support | 1961 |
| Temple Leadworks Limited | Construction | 2006 |
| Temple Mill Residents Limited | Households | 1999 |
| Templewood Consultants Limited | Extraterritorial | 1997 |
| Temprimental Films Ltd | Information & communication | 2015 |
| TEN Recruitment Services Ltd. | Administrative & support | 2021 |
| Tennis the Menace Limited | Professional & scientific | 2007 |
| Terence James Property Trading Limited | Extraterritorial | 2005 |
| Terry Jones Post Productions Limited | Arts & recreation | 1978 |
| Test Busters Ltd | Other services | 2005 |
| Tetra Foundation | Other services | 2023 |