| Secure Shelter Ltd | Households | 2024 |
| Secure-Clean-Solutions Ltd | Administrative & support | 2025 |
| Securedecomm Ltd | Wholesale & retail | 2024 |
| Securefast Limited | Extraterritorial | 1989 |
| Secureguest Ltd | Information & communication | 2025 |
| Securelec Services Limited | Wholesale & retail | 2023 |
| Securequity Ltd | Financial services | 2005 |
| Securetec Fire and Security Systems Limited | Construction | 2018 |
| Secureuk Ltd. | Administrative & support | 2017 |
| Securewise Security Services Limited | Administrative & support | 2020 |
| Securite Limited | Construction | 2000 |
| Securitech Solutions (Sheffield) Ltd | Administrative & support | 2021 |
| Sedawk Dynamics Limited | Information & communication | 2026 |
| Sedge Hospitality Limited | Hospitality | 2025 |
| Seed Support Ltd | Health & social care | 2024 |
| SEED3D Limited | Professional & scientific | 2005 |
| Seedo Afren Ltd | Hospitality | 2024 |
| Seeds to Stars Nursery Ltd | Health & social care | 2015 |
| Seeing Green Tree Co Limited | Agriculture & fishing | 2022 |
| Seekershub Sheffield | Education | 2022 |
| Seekerstream Ltd. | Professional & scientific | 2016 |
| Seener Retail Co., Ltd | Wholesale & retail | 2025 |
| Seeward Ltd | Manufacturing | 2013 |
| SEF Foods Ltd | Administrative & support | 2016 |
| Sefaar Food Limited | Wholesale & retail | 2026 |
| Sefen & Zaky Ltd | Health & social care | 2023 |
| Sefton Armstrong Limited | Administrative & support | 2015 |
| Segie Limited | Health & social care | 2015 |
| Sejemba & Co Ltd | Construction | 2023 |
| Sejslj Ltd | Financial services | 2022 |
| Seked Labs Limited | Manufacturing | 2025 |
| Sekhon & Sons Haulage Ltd | Transport & logistics | 2025 |
| Sekungcono Limited | Administrative & support | 2016 |
| SELCH03 Limited | Information & communication | 2017 |
| Seleba Property Ltd | Real estate | 2023 |
| Select 525 Ltd | Wholesale & retail | 2025 |
| Select Cars Sheffield Limited | Wholesale & retail | 2002 |
| Select Distinct Limited | Professional & scientific | 2021 |
| Select Vehicle Solutions (SVS) Ltd | Administrative & support | 2020 |
| SELENA2024 Ltd | Transport & logistics | 2024 |
| Self Build & Contract Floors Limited | Construction | 2006 |
| Self Defence (UK) Limited | Arts & recreation | 2009 |
| Sell House With US Ltd | Real estate | 2021 |
| Sellars Decorating Limited | Construction | 2017 |
| Seller BEE Limited | Wholesale & retail | 2026 |
| Selling Homes Ltd | Real estate | 2003 |
| Selling My Motor Ltd | Wholesale & retail | 2025 |
| Sellmart Ltd | Wholesale & retail | 2023 |
| Sellweb Limited | Manufacturing | 2007 |
| Selva Fashion Ltd | Wholesale & retail | 2025 |
| Selwood (Rotherham) Management Company Limited | Households | 1983 |
| Semi Logistics Ltd | Transport & logistics | 2020 |
| Semweb Services Ltd | Information & communication | 2015 |
| Sena Barbers Ltd | Other services | 2025 |
| Sencia Limited | Professional & scientific | 1997 |
| Send Futures CIC | Administrative & support | 2023 |
| Senda Family Limited | Construction | 2014 |
| Sendstarz C.I.C. | Health & social care | 2026 |
| Senior Productions Limited | Information & communication | 2011 |
| Senior Property Developments Ltd | Real estate | 2025 |
| Senior Security Systems Limited | Administrative & support | 2023 |
| Sensa Waste Solutions Ltd | Water & waste | 2014 |
| Sense AI Limited | Information & communication | 2020 |
| Sense Mortgages Ltd | Financial services | 2024 |
| Sense Portal Consult Limited | Education | 2022 |
| Sense&Play Ltd | Health & social care | 2026 |
| Sensible Trading Limited | Information & communication | 2020 |
| Sensory Emergency C.I.C. | Health & social care | 2026 |
| Sensoryplus Ltd. | Wholesale & retail | 2017 |
| Sensualspa Beauty Trainings Ltd | Wholesale & retail | 2021 |
| Sensus Coaching Limited | Education | 2017 |
| Sent Into Space Ltd | Information & communication | 2011 |
| Sentience Consulting Limited | Information & communication | 2018 |
| Sentinel Energy Analytics Ltd | Professional & scientific | 2024 |
| Sentinel Training Academy Limited | Administrative & support | 2024 |
| Sentinel Truck Bodies & Trailers Ltd | Manufacturing | 2024 |
| Sento Spa Ltd. | Arts & recreation | 2015 |
| Sentric Group Limited | Financial services | 2025 |
| Sentry Pest Control Limited | Administrative & support | 2024 |
| Sentrymaster Security Ltd | Administrative & support | 2024 |
| SEO Copilot Ltd | Information & communication | 2011 |
| Seodoctor Ltd | Information & communication | 2026 |
| Seoseamh Property Ltd | Real estate | 2020 |
| Sequential Reporting Limited | Administrative & support | 2015 |
| SER BAN Company Ltd | Transport & logistics | 2020 |
| Serdo Ltd | Hospitality | 2026 |
| Serene Events Management Ltd | Administrative & support | 2025 |
| Serene Horizon Property Ltd | Real estate | 2025 |
| Serenepath Home Care Ltd | Health & social care | 2025 |
| Sereniti Limited | Professional & scientific | 2006 |
| Serenity Bleu Limited | Construction | 2021 |
| Serenity Health and Wellbeing Ltd | Health & social care | 2021 |
| Serenity Nails Ltd | Other services | 2014 |
| Serenity Premium Living Limited | Health & social care | 2026 |
| Sereniwell Limited | Wholesale & retail | 2025 |
| Serenora Travel Ltd | Administrative & support | 2026 |
| Serenta Homecare Ltd | Health & social care | 2011 |
| Serginson Testing Solutions Limited | Information & communication | 2004 |
| Sergiu Transport Ltd | Transport & logistics | 2022 |
| Series Three Creative Limited | Information & communication | 2024 |