| Symington Management Limited | Real estate | 2005 |
| Symitry Solutions (UK) Limited | Professional & scientific | 2001 |
| Symmetry Builds Limited | Construction | 2010 |
| Symmetry Park Aston Clinton Management Company Limited | Real estate | 2019 |
| Symmetry Park Bicester Management Company Limited | Other services | 2017 |
| Symmetry Park Biggleswade Management Company Ltd | Real estate | 2020 |
| Symmetry Park Biggleswade Management Company NO 3 Ltd | Real estate | 2024 |
| Symmetry Park Darlington Management Company Ltd | Real estate | 2018 |
| Symmetry Park Doncaster Management Company Limited | Real estate | 2018 |
| Symmetry Park Kettering Management Company Ltd | Real estate | 2022 |
| Symmetry Park Merseyside Management Company Ltd | Real estate | 2022 |
| Symmetry Park Rugby Management Company Ltd | Real estate | 2022 |
| Symmetry-Europe Limited | Professional & scientific | 1993 |
| Symphony Care Limited | Health & social care | 2005 |
| Symz Capital Ltd | Real estate | 2023 |
| Syncplus Ltd | Information & communication | 2010 |
| Syncro GAS and Plumbing Limited | Construction | 2021 |
| Syncro IT Solutions Ltd | Information & communication | 2026 |
| Syncro Office Technology Ltd | Administrative & support | 2015 |
| Syndew Technology Ltd | Information & communication | 2025 |
| Synergasia Enterprise Ltd | Information & communication | 2022 |
| Synergee Consultancy Limited | Administrative & support | 2016 |
| Synergistik Limited | Information & communication | 2023 |
| Synergy Electric Global Limited | Manufacturing | 2025 |
| Synergy Financial Services Limited | Professional & scientific | 2015 |
| Synergy GAS Services Limited | Administrative & support | 2013 |
| Synergy Mobile Limited | Information & communication | 2006 |
| Synergy Plus Recruitment Ltd | Administrative & support | 2024 |
| Syntelic Ltd | Information & communication | 2018 |
| Syntropy Property Ltd | Real estate | 2023 |
| Syon & Lanna Threads Ltd | Manufacturing | 2025 |
| Syon Lounge Ltd | Hospitality | 2014 |
| Sysinfo Consulting Limited | Information & communication | 2010 |
| System 1 Trading Limited | | 2005 |
| System Contracts UK Limited | Construction | 2012 |
| System M IT Ltd | Information & communication | 2015 |
| Systematic Gumption Limited | Information & communication | 2011 |
| Systems + Ceramics Limited | Construction | 1991 |
| Systems HR Ltd. | Information & communication | 2007 |
| Sywell Aerodrome,Limited | Agriculture & fishing | 1933 |
| Sywell Developments Limited | Real estate | 2024 |
| Sywell Garden Machinery Ltd | Wholesale & retail | 2014 |
| Sywell Leisure Sports Limited | Arts & recreation | 1999 |
| Sywell Medical Services Ltd | Health & social care | 2023 |
| Sywell Warehousing Ltd | Transport & logistics | 2010 |
| SZ Private Limited | Hospitality | 2026 |
| Szatko Retail Ltd | Wholesale & retail | 2019 |
| Szed Consulting Limited | Professional & scientific | 2012 |
| Szekely Car Spraying Ltd | Wholesale & retail | 2018 |
| SZR Property Management Ltd | Real estate | 2019 |
| Szupek Trans Ltd | Wholesale & retail | 2016 |
| Szydlo Trans Ltd | Transport & logistics | 2026 |
| T & 2 Sugars Limited | Hospitality | 2023 |
| T & K Cars Shop Ltd | Wholesale & retail | 2020 |
| T & K Precision (Holdings) Limited | Financial services | 2019 |
| T & K Precision 2025 Limited | Financial services | 2025 |
| T & L Global Limited | Wholesale & retail | 2021 |
| T & L Marquee Hire Limited | Administrative & support | 2007 |
| T & S Vehicle Services Ltd | Wholesale & retail | 2016 |
| T Bates Interiors Ltd | Administrative & support | 2007 |
| T Business Ltd | Real estate | 2003 |
| T C Catering Supplies Limited | Transport & logistics | 2005 |
| T Construction Ltd | Construction | 2010 |
| T D F Engineering Ltd | Administrative & support | 2016 |
| T Diamond Limited | Real estate | 2021 |
| T Donnelly Flooring Limited | Construction | 2002 |
| T Eaton Transport Limited | Transport & logistics | 2021 |
| T F K Homes Limited | Real estate | 2002 |
| T J Abbott Limited | Wholesale & retail | 2002 |
| T K Supermarket Ltd | Wholesale & retail | 2024 |
| T L C Sport Limited | Wholesale & retail | 1992 |
| T Lucian Construction Ltd | Construction | 2023 |
| T Matthews Properties Limited | Real estate | 2019 |
| T P Imports Ltd | Wholesale & retail | 2020 |
| T R Brown Holdings Ltd | Financial services | 2026 |
| T Sharpe Windows Ltd | Construction | 2025 |
| T Szydlik Transport Ltd | Transport & logistics | 2019 |
| T T A-Z Logistics Ltd | Transport & logistics | 2026 |
| T West Developments Limited | Construction | 2025 |
| T West Irthlingborough Ltd | Construction | 2024 |
| T&E Complex Ltd | Administrative & support | 2019 |
| T&E Complex Solutions Ltd | Professional & scientific | 2015 |
| T&E Finance Ltd | Professional & scientific | 2026 |
| T&E Group Ltd | Wholesale & retail | 2018 |
| T&E Letting Ltd | Real estate | 2025 |
| T&E Plumbing and Heating Ltd | Construction | 2023 |
| T&M Landscapes Ltd | Administrative & support | 2023 |
| T&T Dwellings Ltd | Real estate | 2023 |
| T'S Events and Social Ltd | Hospitality | 2024 |
| T. Class Security Limited | Administrative & support | 1998 |
| T.& K.Precision Limited | Manufacturing | 1961 |
| T.A.G Leisure Ltd | Hospitality | 2022 |
| T.B. Brickwork Limited | Construction | 2014 |
| T.G Fencing Limited | Construction | 2022 |
| T.K. Cable Limited | Construction | 2003 |
| T.Max LY Limited | Wholesale & retail | 2023 |
| T.R Landscaping Ltd | Administrative & support | 2024 |
| T.R.O.C. Limited | Wholesale & retail | 2014 |
| T.W. Plastering Company Ltd | Construction | 2022 |
| T2 Pinpoint Solutions Ltd | Transport & logistics | 2025 |