| Sisters in Service CIC | Health & social care | 2024 |
| Sistrsthelabel Limited | Wholesale & retail | 2024 |
| Site Cleaning Services (SW) Ltd | Other services | 2016 |
| Site Services (MK) Ltd | Financial services | 2026 |
| Site Tech Limited | Manufacturing | 2019 |
| Site-Services-Solutions Ltd | Manufacturing | 2019 |
| Sitech Support Ltd | Information & communication | 2023 |
| Siteline Productions Ltd | Arts & recreation | 2010 |
| Sitespect Ltd | Information & communication | 2014 |
| Siteworks Events Ltd | Other services | 2026 |
| Sitwell Garage Limited | Wholesale & retail | 1972 |
| SIV Ltd | Wholesale & retail | 2024 |
| SIX ST. James Limited | Real estate | 2024 |
| SIX28 Limited | Information & communication | 2020 |
| Sixerr Ltd. | Information & communication | 2023 |
| Sixty Three Hair Limited | Other services | 2018 |
| Sixty-Four Europe Ltd | Arts & recreation | 2001 |
| SIXTY6 Fitness Ltd | Arts & recreation | 2026 |
| SIXTY6 HOC Ltd | Hospitality | 2026 |
| SIXTY6 Lettings Ltd | Real estate | 2026 |
| SIXTY6 Living Ltd | Real estate | 2023 |
| Sizzla Grill UK Ltd | Hospitality | 2025 |
| Sizzle Spot 786 Ltd | Hospitality | 2025 |
| Sizzle Spot Derby Ltd | Hospitality | 2023 |
| Sizzler Grill (Burton) Ltd | Hospitality | 2025 |
| SJ Glamour Ltd | Wholesale & retail | 2022 |
| SJ Infotech Limited | Information & communication | 2017 |
| SJ Maughan Engineering Ltd | Professional & scientific | 2020 |
| SJ Rehab Limited | Professional & scientific | 2015 |
| SJ Travel (Midlands) Ltd | Transport & logistics | 2022 |
| Sj-Vj Trading Corporation Limited | Wholesale & retail | 2024 |
| Sjad Enterprises Ltd | Transport & logistics | 2019 |
| SJC Joinery Solutions Ltd | Construction | 2026 |
| SJE Master Thatchers Limited | Construction | 2017 |
| SJL (East Midlands) Limited | Professional & scientific | 2024 |
| SJL Flooring Limited | Wholesale & retail | 2021 |
| SJM Joinery Limited | Construction | 2008 |
| Sjr-Ai Ltd | Professional & scientific | 2025 |
| SJS Sheeting Limited | Construction | 2010 |
| SJT Estates Ltd | Real estate | 2024 |
| SK Builders Derby Limited | Construction | 2023 |
| SK Commercials Ltd | Wholesale & retail | 2020 |
| SK Developers Ltd | Real estate | 2019 |
| SK Kitchen Ltd | Hospitality | 2025 |
| SK Midland Builder Ltd | Other services | 2026 |
| SK Plant (Derby) Ltd | Manufacturing | 2022 |
| SK Restaurant Ltd | Hospitality | 2025 |
| SK Sharma Ltd | Transport & logistics | 2025 |
| SK Studios Freelancing Ltd | Information & communication | 2022 |
| SK Tax Accountants Ltd | Professional & scientific | 2026 |
| Skarlat Ltd | Wholesale & retail | 2025 |
| Skate Base UK Limited | Other services | 2014 |
| SKB Beauty (Doncaster) Ltd | Other services | 2023 |
| SKB Property Group Ltd | Professional & scientific | 2026 |
| SKC Consultancy and Accounting Services Limited | Information & communication | 2011 |
| SKC Property Maintenance and Repairs Limited | Households | 2022 |
| Skdl Properties Ltd | Real estate | 2026 |
| Skeen Computing Services Limited | Information & communication | 1986 |
| Skefco Investments Ltd | Real estate | 2024 |
| Skennedybrickwork Limited | Administrative & support | 2025 |
| Skepstudio Ltd | Information & communication | 2021 |
| Sketchal Ltd | Wholesale & retail | 2025 |
| Skgf Limited | Information & communication | 2016 |
| Skgr Limited | Real estate | 2015 |
| Skhd Ltd | Real estate | 2024 |
| SKI Cosy Ltd | Administrative & support | 2015 |
| Skiftoo Ltd | Wholesale & retail | 2025 |
| Skillbase Limited | Administrative & support | 2010 |
| Skilled Search Ltd | Administrative & support | 2023 |
| Skilledge Training Centre Ltd | Education | 2025 |
| Skills Services Ltd | Construction | 2025 |
| Skin & Beauty Studio Limited | Other services | 2025 |
| Skin Code Limited | Health & social care | 2021 |
| Skin Deep by Tash Ltd | Other services | 2024 |
| Skin Secrets Aesthetics Ltd | Other services | 2020 |
| Skinetics Group Ltd | Education | 2025 |
| Skinner & Watson (Properties) Limited | Construction | 2003 |
| Skinner Holidays Ltd | Hospitality | 2024 |
| Skinner Land Ltd | Real estate | 2016 |
| Skinner Properties Ltd | Real estate | 2011 |
| Skinny Cat Properties Ltd | Real estate | 2022 |
| Skinny Media Limited | Information & communication | 2014 |
| Skip Units Limited | Manufacturing | 1995 |
| Skmurefu &Sons Private Ltd | Health & social care | 2025 |
| Sknm Pharma Ltd | Wholesale & retail | 2024 |
| Skpq Properties Limited | Real estate | 2025 |
| SKR Consulting Ltd | Information & communication | 2010 |
| SKR Holdings Limited | Wholesale & retail | 2023 |
| SKR Investments Ltd | Real estate | 2016 |
| SKR Legal Limited | Professional & scientific | 2014 |
| SKS Group of Services Ltd | Construction | 2020 |
| SKT Holdings Limited | Financial services | 2025 |
| Sky Cctv Ltd | Wholesale & retail | 2021 |
| Sky FOX Property Limited | Real estate | 2022 |
| Sky Glass Ltd | Manufacturing | 2024 |
| Sky Gray Windows Ltd | Manufacturing | 2026 |
| Sky High Collectables Ltd | Wholesale & retail | 2026 |
| Sky Shield Services Ltd | Administrative & support | 2025 |
| Sky T&E Limited | Wholesale & retail | 2020 |
| Sky Travel & Limited | Administrative & support | 2022 |