| Sympathetic Care Ltd | Health & social care | 2024 |
| Symphonica Limited | Administrative & support | 2022 |
| Symphony Consulting Ltd | Real estate | 2023 |
| Symphony Domestic Management Ltd | Administrative & support | 2018 |
| Symphony Learning Trust | Education | 2012 |
| Symphonyrooms Limited | Real estate | 2011 |
| Synacq Consulting Limited | Information & communication | 2021 |
| Synapse DN Consulting Ltd | Administrative & support | 2020 |
| Synaptex.Ai Limited | Information & communication | 2024 |
| Synaptic AI Ltd | Information & communication | 2025 |
| Synchronicity Living Ltd | Health & social care | 2025 |
| Syndicate Investments Limited | Extraterritorial | 2023 |
| Syndicate Solutions Limited | Information & communication | 2007 |
| Syndicate Two Ltd | Real estate | 2016 |
| Syneco Ltd | Construction | 2023 |
| Synergi IT Systems Ltd | Information & communication | 2015 |
| Synergy - Mansion Street Limited | Construction | 2026 |
| Synergy AL Limited | Real estate | 2025 |
| Synergy Asset Management Group Limited | Real estate | 2016 |
| Synergy Bathroom Solutions Ltd | Extraterritorial | 2008 |
| Synergy Capital Investments Limited | Real estate | 2016 |
| Synergy CH Ltd | Health & social care | 2025 |
| Synergy Legal Group Limited | Administrative & support | 2023 |
| Synergy Leicester Care and Support Ltd | Health & social care | 2020 |
| Synergy Lets Limited | Real estate | 2019 |
| Synergy NM Limited | Real estate | 2025 |
| Synergy Park Developments Ltd | Construction | 2024 |
| Synergy Personnel Services Limited | Administrative & support | 2011 |
| Synergy Psychology Limited | Education | 2023 |
| Synergy Real Estates Leicester Limited | Real estate | 2018 |
| Synergy Realty Ltd | Real estate | 2021 |
| Synergy Recruitment Solution Limited | Health & social care | 2014 |
| Synergy Refurbs Ltd | Construction | 2026 |
| Synergy RS IND Limited | Administrative & support | 2017 |
| Synergy Stays Ltd | Construction | 2024 |
| Synesis Global Ltd | Wholesale & retail | 2024 |
| Synova Health Ltd | Wholesale & retail | 2025 |
| Synovia Global Ltd | Wholesale & retail | 2025 |
| Synro Ltd | Information & communication | 2025 |
| Syntax Quill Ltd | Wholesale & retail | 2025 |
| Syntax Trading Limited | Wholesale & retail | 2020 |
| Syntaxworxx Ltd | Information & communication | 2025 |
| Syntex Trading Limited | Wholesale & retail | 2019 |
| Syon Advisory Limited | Professional & scientific | 2026 |
| Syon Tax Holdings Limited | Financial services | 2022 |
| Syon Tax Limited | Professional & scientific | 2020 |
| SYR Accommodation Ltd | Real estate | 2023 |
| Syraverse Limited | Information & communication | 2023 |
| Sysc Properties Ltd | Real estate | 2025 |
| Syslynx Limited | Information & communication | 2007 |
| System Xperts Ltd | Information & communication | 2024 |
| Systemlevel Ltd | Information & communication | 2014 |
| Systmit Ltd | Administrative & support | 2016 |
| Syston Cabinet Company Limited | Hospitality | 1976 |
| Syston Euro Stop Ltd | Wholesale & retail | 2025 |
| Syston Family Cellar Limited | Wholesale & retail | 2012 |
| Syston Freight Limited | Transport & logistics | 2008 |
| Syston Glamour Nails Ltd | Other services | 2026 |
| Syston Golden Barbers Ltd | Other services | 2024 |
| Syston Haulage Ltd | Transport & logistics | 2021 |
| Syston House Ltd | Hospitality | 2026 |
| Syston Hub Ltd | Financial services | 2024 |
| Syston Leicester Ltd | Wholesale & retail | 2020 |
| Syston Logistics Limited | Other services | 2010 |
| Syston Masonic Hall Limited | Real estate | 2025 |
| Syston MPV Ltd | Wholesale & retail | 2022 |
| Syston Rolling Shutters Limited | Construction | 1988 |
| Syston Rose Garden Ltd | Hospitality | 2017 |
| Syston Sizzler Ltd | Hospitality | 2018 |
| Syston Staircraft Ltd | Manufacturing | 2025 |
| Syston SUB Ltd | Hospitality | 2022 |
| Syston Taxis Ltd | Transport & logistics | 2022 |
| Syston Water Services Ltd | Administrative & support | 2005 |
| SYT Medical Ltd | Health & social care | 2013 |
| Sytner Automobiles Limited | Professional & scientific | 2003 |
| Sytner Automotive Limited | Wholesale & retail | 1986 |
| Sytner Cars Limited | Wholesale & retail | 1993 |
| Sytner Group Services Limited | Administrative & support | 1978 |
| Sytner Leasing Limited | Professional & scientific | 1989 |
| Sytner Motability Limited | Wholesale & retail | 2009 |
| Sytner Motors Limited | Professional & scientific | 1960 |
| Sytner Retail Limited | Wholesale & retail | 1965 |
| Sytner Select Limited | Professional & scientific | 1951 |
| Sytner Transport Limited | Real estate | 1988 |
| Sytner Vehicle Management Limited | Professional & scientific | 1995 |
| Sywell Adept Ltd | Hospitality | 2016 |
| SYZ Consulting Services Limited | Professional & scientific | 2019 |
| SZ Masterbuild Ltd | Construction | 2025 |
| SZ Portfolios Limited | Real estate | 2025 |
| SZ S Builders Limited | Construction | 2024 |
| SZ Solutions Limited | Professional & scientific | 2015 |
| Szechuan House Limited | Hospitality | 2024 |
| Szechwanspice Ltd | Hospitality | 2024 |
| SZL Investments Limited | Real estate | 2019 |
| Szyszka Trans Ltd | Transport & logistics | 2019 |
| T & a Consultants (UK) Limited | Financial services | 2016 |
| T & a Footwear Limited | Wholesale & retail | 2004 |
| T & a Karigar Ltd | Real estate | 2024 |
| T & a Shoe Limited | Wholesale & retail | 2004 |
| T & F Asset Management Limited | Professional & scientific | 2024 |