| Site Sealed Delivered Ltd | Construction | 2025 |
| Site Sharp Ltd | Other services | 2019 |
| Sitekrafter Ltd | Information & communication | 2025 |
| SIX Contract Furniture Ltd | Manufacturing | 2016 |
| SIX the Residence Limited | Wholesale & retail | 2020 |
| SJ Mosley Ltd | Professional & scientific | 2022 |
| SJB Computer Services Limited | Other services | 2003 |
| SJH Medical Services Ltd | Health & social care | 2020 |
| SJW1990 Holdings Ltd | Financial services | 2022 |
| SK Rail 1 Limited | Transport & logistics | 2017 |
| Sk&Sm Property Holdings Limited | Real estate | 2026 |
| SKA Financial Consultancy Ltd | Professional & scientific | 2019 |
| Skelding Properties Ltd | Real estate | 2025 |
| Sketch Scheme Limited | Professional & scientific | 2009 |
| Skidmore Property Services Limited | Real estate | 2020 |
| SKS Bruce Limited | Construction | 2015 |
| Skydent Limited | Administrative & support | 2018 |
| Skyline Overseas UK Limited | Education | 2022 |
| SL Locum Services Limited | Health & social care | 2004 |
| SLB Consultancy Ltd | Professional & scientific | 2025 |
| Sleep Cult Ltd | Wholesale & retail | 2025 |
| SM Management Support Services Ltd | Professional & scientific | 2022 |
| SM Pro Solutions Limited | Health & social care | 2018 |
| Smalta Limited | Wholesale & retail | 2024 |
| Smart Property Repairs Limited | Manufacturing | 2018 |
| Smart Steps Ltd | Education | 2023 |
| Smartsec Security Systems Ltd | Administrative & support | 2021 |
| Smarty Pants @ LYE Limited | Education | 2017 |
| Smash BAG Limited | Manufacturing | 2025 |
| Smiling Faces Limited | Wholesale & retail | 2001 |
| Smith & Pepper Jewels Limited | Manufacturing | 2020 |
| Smiths Automotive Electrical Services Ltd | Wholesale & retail | 2026 |
| Smiths Developments Ltd | Hospitality | 2013 |
| Snackz Ltd | Wholesale & retail | 2025 |
| Snapes Building Services Ltd | Construction | 2025 |
| Snapspace Holdings Limited | Real estate | 2024 |
| Snatchbacks Media Ltd | Administrative & support | 2013 |
| Sneeyeg Limited | Information & communication | 2023 |
| Snippet Consulting Ltd | Information & communication | 2022 |
| Snippet Digital Ltd | Information & communication | 2020 |
| Soccer Ltd | Arts & recreation | 2018 |
| Social Bubble Limited | Extraterritorial | 2020 |
| Social Eats Events Ltd | Hospitality | 2021 |
| Social Impact Associates Ltd | Professional & scientific | 2023 |
| Sodium & Co Ltd | Professional & scientific | 2023 |
| Sofa Designs Midlands Ltd | Manufacturing | 2025 |
| Soft Play Maintenance Limited | Manufacturing | 2020 |
| Sogno Holdings Ltd | Real estate | 2023 |
| Sohal (UK) Limited | Wholesale & retail | 2003 |
| Sohal Property Investments Limited | Real estate | 2020 |
| SOI Siam Ltd | Hospitality | 2024 |
| Solid Bond Constructions Limited | Construction | 2015 |
| Soloply Limited | Financial services | 1981 |
| Solutions Work Limited | Professional & scientific | 1997 |
| Solve Advisory Ltd | Professional & scientific | 2023 |
| Somers Group Limited | Financial services | 2021 |
| Sonada Beds Ltd | Wholesale & retail | 2021 |
| Sonder & Seek Ltd | Professional & scientific | 2021 |
| Sospitas Ltd | Professional & scientific | 2014 |
| Soteriasafetytraining Ltd | Education | 2025 |
| Soul Trip Ltd | Administrative & support | 2025 |
| South Manor Ltd | Real estate | 2019 |
| Southall Power Consultancy Services Limited | Energy | 2018 |
| Sovereign Consultants Limited | Professional & scientific | 2023 |
| SP Investco Limited | Real estate | 2020 |
| Spacesaver Bedrooms Ltd | Construction | 2018 |
| Spacesaver Products Limited | Extraterritorial | 2015 |
| Spades N Shears Services UK Ltd | Administrative & support | 2020 |
| Spaghetti Beau Studio Limited | Information & communication | 2015 |
| Spar Property Investment Limited | Real estate | 2025 |
| Sparks Walters Paper Company Ltd | Wholesale & retail | 2023 |
| Spearhead Development Group Limited | Construction | 2020 |
| Special Looks Limited | Wholesale & retail | 2002 |
| Specialist Storage Products Ltd | Wholesale & retail | 2021 |
| Specialist Surveyors Limited | Water & waste | 2002 |
| Spectraserve Limited | Water & waste | 2017 |
| Spectre Visuals Limited | Information & communication | 2022 |
| Spectrum Inspection Services Limited | Administrative & support | 2009 |
| Spencer Estates Limited | Hospitality | 1983 |
| Spencer Green & Company Ltd | Construction | 2025 |
| Spice of Wollaston Ltd | Hospitality | 2019 |
| Spice Village Ltd | Hospitality | 2025 |
| Spicex Enterprise Limited | Hospitality | 2025 |
| Spin Fast Laundry Linen Services Ltd | Other services | 2021 |
| Spinfast Domestic Laundry Ltd | Other services | 2025 |
| Spiyda Ltd | Manufacturing | 2016 |
| Splash Luxury Bathrooms Limited | Administrative & support | 2004 |
| Split Holdings Limited | Administrative & support | 2018 |
| Spoof Arts Ltd | Wholesale & retail | 2017 |
| Sportora Ltd | Administrative & support | 2026 |
| Sports 4 YOU Ltd | Arts & recreation | 2011 |
| Sports Avenue Limited | Wholesale & retail | 2012 |
| Spring Street Books Ltd | Information & communication | 2024 |
| SPRINTECH3D Ltd | Professional & scientific | 2019 |
| Sprocket Design Limited | Information & communication | 2015 |
| Sprocket Property Limited | Real estate | 2021 |
| Spur Engineering Limited | Professional & scientific | 2025 |
| Squid Incorporated Ltd | Wholesale & retail | 2023 |
| Squiggles Day Care & Activity Club Ltd | Health & social care | 2010 |
| SR Landscape Architecture Limited | Professional & scientific | 2022 |