| Silver Tree Joinery Ltd | Construction | 2020 |
| Silverbond Developments Limited | Construction | 2011 |
| Silvercrest Trading Limited | Wholesale & retail | 2005 |
| Silverhaze Holdings Limited | Real estate | 1970 |
| Silverstar Direct Ltd | Wholesale & retail | 2022 |
| Silverstar Real Estate Ltd | Real estate | 2019 |
| Silvesters Electrical Contractors Ltd | Construction | 2010 |
| SIM Bhatoy Limited | Information & communication | 2023 |
| Simaa Consulting Limited | Information & communication | 2015 |
| Simard Limited | Administrative & support | 2008 |
| Simbaexpress Ltd | Transport & logistics | 2026 |
| Simbiso Community Services | Health & social care | 2018 |
| Simi’S Delight Catering Ltd | Hospitality | 2025 |
| Simmons Solutions Ltd | Other services | 2026 |
| Simms Ventilation Services Ltd | Construction | 2023 |
| Simon Blyth Estate Agents (Huddersfield) Limited | Real estate | 1999 |
| Simon Bolton Services Ltd | Construction | 2022 |
| Simon Calvert Contractors Limited | Construction | 1999 |
| Simon H Wilson and Associates Ltd | Information & communication | 2026 |
| Simon Mooney Photo Limited | Information & communication | 2001 |
| Simonis Agrochemicals UK Ltd | Manufacturing | 2021 |
| Simple Housing UK Ltd | Real estate | 2011 |
| Simple Maintenance Services Limited | Construction | 2018 |
| Simple Sleep Solutions Ltd | Manufacturing | 2020 |
| Simple Solutions (Chemicals) Limited | Extraterritorial | 2015 |
| Simplicio Zimhete Transport Ltd | Transport & logistics | 2026 |
| Simpliciter Technology Ltd | Information & communication | 2022 |
| Simplifai Limited | Extraterritorial | 2019 |
| Simplifai Systems Limited | Information & communication | 2017 |
| Simply Architectural Limited | Professional & scientific | 2013 |
| Simply BIZ Mortgages Limited | Financial services | 2003 |
| Simply BIZ Services Limited | Financial services | 2002 |
| Simply Business Solutions Limited | Professional & scientific | 2008 |
| Simply Fundraising Limited | Information & communication | 2023 |
| Simply Garden Ltd | Extraterritorial | 2026 |
| Simply Laundry ( NE ) Ltd | Administrative & support | 2023 |
| Simply Lighting Limited | Wholesale & retail | 2003 |
| Simply Made Developments Ltd | Construction | 2019 |
| Simply PVC Limited | Construction | 2008 |
| Simply Sandwich'D Ltd | Hospitality | 2026 |
| Simply Silver Collections Limited | Wholesale & retail | 1999 |
| Simply Solar Sense Ltd | Construction | 2011 |
| Simply Wigs Limited | Other services | 2008 |
| Simplybiz Asset Management Limited | Financial services | 2009 |
| Simplybiz Investments Limited | Financial services | 2009 |
| Simpson Dennis Roofing Services Ltd | Construction | 2021 |
| Simpson Wood (Financial Services) Limited | Financial services | 2003 |
| Simpson Wood (Holdings) Limited | Professional & scientific | 2017 |
| Simpson Wood Financial Services Leeds Limited | Financial services | 2025 |
| Simpson Wood Limited | Professional & scientific | 2014 |
| Simran Marketing Management Ltd | Administrative & support | 2017 |
| Sinclair Harding (UK) Limited | Manufacturing | 1995 |
| Sindicate Records Ltd | Wholesale & retail | 2022 |
| Sine Works Limited | Manufacturing | 2023 |
| Singh Fight Promotions Ltd | Arts & recreation | 2019 |
| Singh Sahib Associate Ltd | Real estate | 2024 |
| Single Thread Ltd | Professional & scientific | 2022 |
| Single Thread Tech Ltd | Administrative & support | 2026 |
| Singleton Autos Ltd | Wholesale & retail | 2021 |
| Sinister Gifts Limited | Wholesale & retail | 2022 |
| Sirah Pharma Ltd | Health & social care | 2022 |
| Sirocco Avenue Ltd | Wholesale & retail | 2022 |
| Sirpa Ltd | Health & social care | 2013 |
| Sirraph Property Company Limited | Real estate | 2026 |
| Siruss Holdings Ltd | Hospitality | 2024 |
| Sistours Ltd | Administrative & support | 2023 |
| Site Patrol Security (UK) Limited | Administrative & support | 2011 |
| Site Sniper Limited | Administrative & support | 2014 |
| Site Spray Services Limited | Professional & scientific | 2024 |
| Sizzlewick Ltd | Wholesale & retail | 2024 |
| SJ Autos & SON Ltd | Wholesale & retail | 2025 |
| SJ Malhi Ltd | Transport & logistics | 2026 |
| SJ Medical Ltd | Health & social care | 2010 |
| SJ Square Limited | Wholesale & retail | 2022 |
| SJC Pharma Ltd | Health & social care | 2021 |
| SJH Investments Ltd | Real estate | 2021 |
| SJH Joinery & Maintenance Ltd | Construction | 2024 |
| SJL3 Ltd | Real estate | 2016 |
| SJM (Almondbury) Limited | Wholesale & retail | 2021 |
| SJM Cleaning Ltd | Administrative & support | 2015 |
| SJM Dampcoursing and Building Contractors Ltd | Construction | 2019 |
| SJR Electrical Contractors Limited | Construction | 2020 |
| SJW Flour Mill and Bakery Services Ltd | Administrative & support | 2005 |
| SK Consultancy PMC Ltd | Extraterritorial | 2017 |
| SK Cookware Ltd | Wholesale & retail | 2023 |
| SK Luxury Interiors Ltd | Wholesale & retail | 2023 |
| SK Luxury Living Ltd | Wholesale & retail | 2022 |
| SK Outlet Limited | Wholesale & retail | 2019 |
| SK Speedy Haulage Ltd | Transport & logistics | 2026 |
| SK Turab Limited | Transport & logistics | 2025 |
| SK Yarns Ltd | Wholesale & retail | 2019 |
| SKA Developments Limited | Real estate | 2016 |
| SKA Holdings Limited | Administrative & support | 2008 |
| SKA Property Management Company Limited | Construction | 2001 |
| Skelmanthorpe Cars Ltd | Transport & logistics | 2009 |
| Skelmanthorpe Family Doctors Limited | Health & social care | 2024 |
| Skelmanthorpe Food Company Limited | Hospitality | 2025 |
| Skelmanthorpe Travel Ltd | Transport & logistics | 2022 |
| SKILLS42 (SE) Ltd | Education | 2026 |
| Skillsphere Ecom Ltd | Wholesale & retail | 2026 |