| Simply Home Rewires Ltd | Construction | 2014 |
| Simplydba Services Limited | Information & communication | 2007 |
| Simpson & Liddard Limited | Manufacturing | 2021 |
| Simpson Skip Hire Ltd | Administrative & support | 2002 |
| Simpsons London LLP | | 2015 |
| Sims Sports Management Limited | Arts & recreation | 2015 |
| Sina Live Ltd | Arts & recreation | 2026 |
| Singal Advisory Ltd | Professional & scientific | 2026 |
| Singer's Interiors Ltd | Manufacturing | 2024 |
| Singers Corporate Asset Finance Limited | Financial services | 2009 |
| Singers Healthcare Finance Limited | Financial services | 1970 |
| SIR EVE Wood Ltd | Hospitality | 2026 |
| Siri Technology Solutions Limited | Information & communication | 2010 |
| Site Pack Pro Ltd | Information & communication | 2026 |
| Siva Properties Limited | Real estate | 2023 |
| Sivaraman Investments Limited | Real estate | 2021 |
| Sivaraman Limited | Health & social care | 2010 |
| Sixteenth Productions Ltd | Information & communication | 2025 |
| Sixth House Pilates Ltd | Education | 2024 |
| SJB Mechanical & Building Services Limited | Construction | 2009 |
| SJC Consultancy Essex Ltd | Professional & scientific | 2026 |
| Sjfes Ltd | Professional & scientific | 2024 |
| SJG Property Services Ltd | Construction | 2020 |
| SJI Greengrocers Ltd. | Wholesale & retail | 2006 |
| SJL Engineers Limited | Administrative & support | 2018 |
| SJT Consultants Limited | Professional & scientific | 2019 |
| SK Brentwood Ltd | Other services | 2025 |
| SK1970 Holdings Ltd | Financial services | 2025 |
| Skanda Tech Ltd | Information & communication | 2024 |
| Skelston Limited | Information & communication | 2003 |
| Skillio World Ltd | Manufacturing | 2025 |
| Skills Growth Ltd | Education | 2021 |
| Skimglade Limited | Professional & scientific | 1981 |
| Skin Alchemy Clinic Limited | Other services | 2024 |
| Skin Art Solutions Ltd | Other services | 2019 |
| Skin Wrkout Ltd | Wholesale & retail | 2023 |
| SKM Dentistry Ltd | Health & social care | 2011 |
| SKS Lettings Limited | Households | 2018 |
| Sky Container Trading Limited | Extraterritorial | 2003 |
| Skyeblu Limited | Financial services | 2013 |
| Skylight Express Suffolk Ltd | Construction | 2026 |
| Skyline 120 Management Limited | Real estate | 2005 |
| Skyline 120 Nexus Management Limited | Real estate | 2010 |
| Skyrooms Co (LDN) Ltd | Manufacturing | 2022 |
| Skyway Investments Ltd | Wholesale & retail | 2019 |
| SL Green Ltd | Real estate | 2024 |
| Slainte Bars Limited | Hospitality | 2019 |
| Slatar Ltd | Construction | 2019 |
| Slater and Sons Construction Ltd | Construction | 2021 |
| SLG Portfolio Ltd | Real estate | 2022 |
| SLH Construction Ltd | Construction | 2015 |
| SLI European Services Limited | Financial services | 2017 |
| Slick Tech Ltd. | Information & communication | 2017 |
| SLJ Property Group Ltd | Real estate | 2022 |
| Slocal Life Ltd | Wholesale & retail | 2019 |
| Sludge Pipe Games Ltd | Information & communication | 2024 |
| Slurp IT Limited | Hospitality | 2025 |
| SM Global Consultancy Limited | Administrative & support | 2019 |
| Small Acre Residents Management Company Limited | Households | 2018 |
| Small World Smart Investments Ltd | Financial services | 2024 |
| Small-Big Solutions Ltd | Other services | 2019 |
| Smart Auto Cars Ltd | Wholesale & retail | 2025 |
| Smart Global Logistics Ltd | Transport & logistics | 2020 |
| Smart Golf Holidays Limited | Administrative & support | 2025 |
| Smart Tech Energy Ltd | Administrative & support | 2023 |
| Smart Tech Energy Services Limited | Other services | 2025 |
| Smarter Investments Limited | Real estate | 2021 |
| Smartfaith Limited | | 1992 |
| Smartphone Group Limited | Wholesale & retail | 2017 |
| Smartpoint Paving Ltd | Construction | 2022 |
| Smartte Limited | Administrative & support | 2016 |
| Smarty Pants Embroidery Ltd | Manufacturing | 2025 |
| SMB Canopies Ltd | Wholesale & retail | 2020 |
| SMB Inc Property Ltd | Real estate | 2021 |
| SMC Coaching & Development Limited | Professional & scientific | 2017 |
| Smcg Property Ltd | Real estate | 2018 |
| SME B2B Group Ltd | Financial services | 2019 |
| SMG Designer Fabrics Ltd | Wholesale & retail | 2025 |
| SMH Events Ltd | Transport & logistics | 2023 |
| Smile Caribbean Group Travel Limited | Administrative & support | 2009 |
| Smith & Sayer Ltd | Real estate | 2021 |
| SMJ Motors Ltd | Wholesale & retail | 2021 |
| Smoking Monkey Productions Ltd | Information & communication | 2012 |
| Smooth Pass Training Limited | Education | 2013 |
| SMS Consultants Ltd | Professional & scientific | 2008 |
| SMT ENF Services Ltd | Construction | 2020 |
| Smug Media Limited | Administrative & support | 2010 |
| SMY Property & Investment Co. Limited | Real estate | 2015 |
| SN Core Ltd | Administrative & support | 2024 |
| Snapwright Advertising Ltd | Professional & scientific | 2025 |
| Snoop & FLO Limited | Other services | 2016 |
| SNR Electrical Ltd | Construction | 2025 |
| Social Lynx Limited | Construction | 2025 |
| Sodha and Daughters Limited | Administrative & support | 2019 |
| Soft in Love Studios Ltd | Arts & recreation | 2025 |
| Softroom (Holdings) Limited | Financial services | 2013 |
| Softroom Limited | Professional & scientific | 1995 |
| Soidea Limited | Wholesale & retail | 2014 |
| Solar Charged Solutions Ltd | Energy | 2021 |
| Solar Gleam Limited | Administrative & support | 2023 |