| Synarchy Partners LLP | | 2021 |
| Synergia Innovations Limited | Extraterritorial | 2023 |
| Synergy Corporate Holdings Ltd | Extraterritorial | 2009 |
| Synergy Estates (SE) Limited | Extraterritorial | 2021 |
| Synergy FM (SE) Limited | Extraterritorial | 2021 |
| Synergy Resourcing International Limited | Administrative & support | 1993 |
| Synergyarb Limited | Professional & scientific | 2024 |
| Syntegro Business Solutions Limited | Professional & scientific | 2011 |
| Syoc Ltd | Construction | 2024 |
| Sypsos Digital Marketing Ltd | Information & communication | 2019 |
| Sysco Europe IHB Limited | Financial services | 2025 |
| Sysco GB Limited | Wholesale & retail | 1986 |
| Sysco UK Finance Limited | Financial services | 2016 |
| Sysco UK Holdings II Limited | Financial services | 2025 |
| Sysco UK Holdings III Limited | Financial services | 2025 |
| Sysco UK Holdings Limited | Financial services | 2016 |
| Sysero Ltd | Information & communication | 2007 |
| SYSTEM6IX Ltd | Professional & scientific | 2024 |
| SYT Bros Limited | Hospitality | 2015 |
| SYT Investments Limited | Real estate | 2022 |
| Szabo Drywall Solutions Ltd | Construction | 2019 |
| T & B Homes Limited | Construction | 2023 |
| T & L Bennett Skips Ltd | Water & waste | 2017 |
| T & T Auctions Limited | Wholesale & retail | 2011 |
| T a Operations Ltd | Professional & scientific | 2020 |
| T and C Plant Operators Ltd | Extraterritorial | 2017 |
| T and K Global Limited | Wholesale & retail | 2021 |
| T Cheshire Associates Ltd | Professional & scientific | 2019 |
| T Denne and Sons Group (Holdings) Limited | Financial services | 2017 |
| T Gardener Ltd | Agriculture & fishing | 2016 |
| T H Brown & SON Limited | Wholesale & retail | 2011 |
| T H Tutoring Ltd | Education | 2023 |
| T M Contract Services Ltd | Administrative & support | 2016 |
| T M Lamb & Sons Ltd | Wholesale & retail | 2026 |
| T Markham Limited | Real estate | 2014 |
| T R Tankers Ltd | Water & waste | 2026 |
| T U R Limited | Professional & scientific | 2003 |
| T W Services (Kent) Limited | Administrative & support | 2004 |
| T&M Grab and Digger Hire Ltd | Water & waste | 2016 |
| T&M Mobile Homes Ltd | Administrative & support | 2017 |
| T&P Inc Ltd | Transport & logistics | 2009 |
| T&R Autos Takeley Limited | Wholesale & retail | 2019 |
| T&S Landscapers, Fencing, Plastering and Roofing Ltd | Administrative & support | 2025 |
| T. Denne and Sons (Holdings) Limited | Wholesale & retail | 1913 |
| T.A Books Ltd | Professional & scientific | 2019 |
| T.C. Tyres & Exhausts Limited | Wholesale & retail | 2003 |
| T.D. Boxall Limited | Agriculture & fishing | 1989 |
| T.G. Claymore (UK) Limited | Construction | 1986 |
| T.I.M.C. Independent Financial Advisers Limited | Financial services | 2003 |
| T.J.R People Consultancy Ltd | Administrative & support | 2022 |
| T.M.L.E. Limited | Professional & scientific | 2012 |
| T.P.S. Holdings (Kent) Limited | Financial services | 2021 |
| T3 Tutoring Ltd | Education | 2017 |
| T6 Innovations Ltd | Manufacturing | 2018 |
| T6 Racing Ltd | Manufacturing | 2024 |
| TAB Detailing Ltd | Professional & scientific | 2017 |
| Tablec Ltd | Health & social care | 2021 |
| TAC Trading (UK) Limited | Information & communication | 2011 |
| Tackle Solutions Limited | Information & communication | 2007 |
| Tadima Ltd | Real estate | 2021 |
| Tailor & Flit Limited | Administrative & support | 2023 |
| Tailor Made Interiors Ltd | Manufacturing | 2025 |
| Tailor Made Stairs Ltd | Construction | 2021 |
| Tails From ME to YOU Productions Ltd. | Information & communication | 2023 |
| Tails on the Street Ltd | Wholesale & retail | 2025 |
| Tailwind Consulting Limited | Information & communication | 2014 |
| Tait Tree Surgery Ltd | Administrative & support | 2023 |
| Take Control Solutions Ltd | Health & social care | 2010 |
| Talbridge Co. Ltd | Administrative & support | 2022 |
| Talent Assist Ltd | Administrative & support | 2023 |
| Talent Dynamics Limited | Professional & scientific | 2001 |
| Talent Hunters Global Ltd | Wholesale & retail | 2023 |
| Talent Leaders Ltd | Administrative & support | 2021 |
| Talented Recruiters Limited | Administrative & support | 2005 |
| Talentgenix Ltd | Administrative & support | 2024 |
| Tales From Mother Earth Limited | Information & communication | 2021 |
| Talis Financial Advisers Ltd | Financial services | 1991 |
| Talk Buddy Ltd | Health & social care | 2023 |
| Talk Loud Productions Ltd | Professional & scientific | 2022 |
| Talk on the Wild Side Ltd | Education | 2026 |
| Tallday Limited | Construction | 2009 |
| Tallman Inc Limited | Professional & scientific | 2013 |
| Tally HO Meadow Ltd | Hospitality | 2026 |
| Talvel Ltd | Information & communication | 2025 |
| Tamose Limited | Professional & scientific | 2009 |
| Tandem Business Media Ltd | Information & communication | 2018 |
| Tandem Media Ltd | Information & communication | 2016 |
| Tandoori Nights TAJ Mahal Ltd | Hospitality | 2019 |
| Tanelorn Limited | Information & communication | 1996 |
| Tango'D Sunbeds Ltd | Health & social care | 2023 |
| Tania Raphael Ltd | Health & social care | 2024 |
| Tank and Container Storage Logistics Ltd | Other services | 2020 |
| Tankbridge Holdings Ltd | Real estate | 2023 |
| Tanners Transport and Storage Limited | Transport & logistics | 2026 |
| Tanton Enterprise Ltd | Wholesale & retail | 2021 |
| Tantsi Limited | Health & social care | 2013 |
| Tantuddy Kitchen Ltd | Hospitality | 2025 |
| TAP 17 Limited | Hospitality | 2021 |
| Tapered Fit LLP | | 2020 |
| Taplocaluk Ltd | Information & communication | 2026 |