| Synechis Ltd | Information & communication | 2012 |
| Synergenix Limited | Wholesale & retail | 2023 |
| Synergi Services Ltd | Transport & logistics | 2023 |
| Synergy Body & Mind Ltd | Health & social care | 2024 |
| Synergy Community Wellbeing CIC | Other services | 2026 |
| Synergy Computing Limited | Information & communication | 1995 |
| Synergy Creative Property Solutions Ltd | Real estate | 2024 |
| Synergy Demolition Group Ltd | Construction | 2016 |
| Synergy Design (Leeds) Ltd | Professional & scientific | 2021 |
| Synergy Education Services Ltd | Professional & scientific | 2023 |
| Synergy FM Ltd | Administrative & support | 2021 |
| Synergy Heating & Renewables Ltd | Construction | 2025 |
| Synergy Medicine Limited | Health & social care | 2018 |
| Synergy Prime Holdings Ltd | Wholesale & retail | 2024 |
| Synergy Project Consulting Ltd | Information & communication | 2018 |
| SYNERGY7 Consultants Ltd | Administrative & support | 2022 |
| SYNERGY778 Ltd | Administrative & support | 2017 |
| Synhrgy Growth Consultants Limited | Professional & scientific | 2023 |
| Synlogic Solutions Limited | Other services | 2012 |
| Synmorice Limited | Wholesale & retail | 2025 |
| Synnex Limited | Wholesale & retail | 2023 |
| Syno Limited | Education | 2012 |
| Synoptik Limited | Arts & recreation | 2003 |
| Synova Innovated Systems Ltd | Construction | 2026 |
| Syntaxia Ltd | Professional & scientific | 2016 |
| Syntegon Telstar UK Ltd | Manufacturing | 1993 |
| SYR Consulting Limited | Professional & scientific | 2017 |
| Syrenka Supermarket Ltd | Wholesale & retail | 2025 |
| Syrian Market Ltd | Wholesale & retail | 2024 |
| Syroid Limited | Information & communication | 2018 |
| Syron Selling Solutions Ltd | Wholesale & retail | 2025 |
| Syrox Global Ltd | Wholesale & retail | 2026 |
| Syrus Pizza Ltd | Hospitality | 2025 |
| Sys-Control Ltd | Arts & recreation | 2025 |
| Sys-Tel Communications Limited | Information & communication | 2023 |
| Sysstar Limited | Administrative & support | 2016 |
| System Earth Limited | Information & communication | 2023 |
| Systemisk Psychology Ltd | Health & social care | 2024 |
| Systemwork CS Limited | Information & communication | 2010 |
| Syth Jasi Limited | Health & social care | 2014 |
| SZ Modelling Limited | Other services | 2023 |
| SZC Services Limited | Other services | 2025 |
| SZM Pharm Services Ltd | Health & social care | 2024 |
| SZR Foods Ltd | Hospitality | 2024 |
| Szsheikh Legal Services Ltd | Professional & scientific | 2025 |
| Szubryt Ltd | Administrative & support | 2018 |
| T & a Precision Plastics Limited | Manufacturing | 2015 |
| T & a Property Holdings Ltd | Real estate | 2017 |
| T & B Valeting Services Limited | Other services | 2020 |
| T & E Development Limited | Construction | 2015 |
| T & M Fried Chicken Ltd | Hospitality | 2017 |
| T & N Mixers Limited | Transport & logistics | 2014 |
| T & P Vehicles Ltd | Wholesale & retail | 2019 |
| T & S Property Managements Ltd | Real estate | 2025 |
| T & T Chinese Takeaway Limited | Hospitality | 2023 |
| T a Morrow Ltd | Financial services | 2023 |
| T a Training Organisation C.I.C. | Education | 2016 |
| T and MW Properties Limited | Real estate | 2013 |
| T B Leeds Limited | Hospitality | 2021 |
| T B Slips Limited | Hospitality | 2009 |
| T Bentley Holdings Limited | Financial services | 2024 |
| T C M Leeds Limited | Wholesale & retail | 2025 |
| T C Salvage Limited | Transport & logistics | 2003 |
| T Chippy Armley Ltd | Hospitality | 2026 |
| T Chippy Ltd | Hospitality | 2025 |
| T Cohen Consult Ltd | Professional & scientific | 2026 |
| T D I Corporation Limited | Real estate | 1998 |
| T Duckworth Property Ltd | Real estate | 2025 |
| T G Restaurants Limited | | 1988 |
| T G Wood Limited | Manufacturing | 1999 |
| T Goldthorpe Holdings Ltd | Financial services | 2023 |
| T Group Capital Ltd | Administrative & support | 2024 |
| T H Daniels Executive Search Limited | Administrative & support | 2019 |
| T Howes Limited | Construction | 2006 |
| T I B Properties Limited | Real estate | 2004 |
| T I Recovery Ltd | Transport & logistics | 2023 |
| T I Security Limited | Administrative & support | 1975 |
| T J Madhouse | Financial services | 2019 |
| T J S Construction Leeds Ltd | Construction | 2022 |
| T J Stafford Ltd | Hospitality | 2021 |
| T Josselyn Consultancy Ltd | Information & communication | 2013 |
| T Kelly Electrical Ltd | Construction | 2022 |
| T King Construction Limited | Construction | 2008 |
| T L a Catering Engineers Limited | Manufacturing | 2008 |
| T M E Agency Limited | Administrative & support | 2009 |
| T Morris Holdings Limited | Financial services | 2023 |
| T P Harris Plumbing and Heating Limited | Construction | 2013 |
| T P Property Services Limited | Real estate | 1998 |
| T Pritchard Services Ltd | Construction | 2017 |
| T R Anaesthesia Ltd. | Health & social care | 2012 |
| T Riley Transport Limited | Transport & logistics | 2004 |
| T S Atkinson Limited | Financial services | 1959 |
| T S Glenfort Limited | Wholesale & retail | 1988 |
| T S Gray Holdings Ltd | Financial services | 2025 |
| T S Investment Holdings Limited | Real estate | 2014 |
| T S Plant & Equipment Hire Ltd | Administrative & support | 2022 |
| T T T Properties (Yorkshire) Ltd | Real estate | 2007 |
| T Twardoch 13 Ltd | Transport & logistics | 2018 |
| T W S Construction (UK) Ltd | Construction | 2013 |
| T Wheatley Limited | Professional & scientific | 2025 |