| Signate Legal Ltd | Professional & scientific | 2019 |
| Signature Conservatories Limited | Construction | 2007 |
| Signature Facility Solutions Ltd | Administrative & support | 2026 |
| Signature JD Pubs Limited | Hospitality | 2016 |
| Signature Marquees & Events Ltd | Construction | 2023 |
| Signature Marquees Limited | Construction | 2013 |
| Signature RS Ltd | Wholesale & retail | 2025 |
| Signature Signs and Print Limited | Manufacturing | 2020 |
| Signature Styles Fashion Store Limited | Wholesale & retail | 2025 |
| Signode UK Ltd | Administrative & support | 2010 |
| Signs and Banners 2 Go Ltd | Manufacturing | 2021 |
| Sikh Student Learning Limited | Education | 2018 |
| Silenza Ltd | Wholesale & retail | 2025 |
| Siliconhagen UK Ltd | Information & communication | 2023 |
| Silkman Property Limited | Real estate | 2026 |
| Silvadale Services Limited | Households | 1990 |
| Silver Knight Garage Ltd | Wholesale & retail | 2005 |
| Silver Knight Haulage and Machineries Ltd | Transport & logistics | 2004 |
| Silver Leaf Ltd | Wholesale & retail | 2021 |
| Silverback CBD Ltd | Wholesale & retail | 2021 |
| Silverback Shows Ltd | Arts & recreation | 2024 |
| Silverphone Ltd | Wholesale & retail | 2025 |
| Silverscreen UK Limited | Manufacturing | 2008 |
| Silvertrophy.Com Ltd | Wholesale & retail | 2000 |
| Sima Systems Limited | Information & communication | 2012 |
| Simba Foods Limited | Wholesale & retail | 2022 |
| Simcox Construction & Conversions Ltd | Construction | 2021 |
| Simicare (Subco) Limited | Health & social care | 2023 |
| Simicare Limited | Health & social care | 2005 |
| Simjor Ltd | Real estate | 2023 |
| Simmons Commercial Property Limited | Real estate | 2020 |
| Simms Creative Ltd | Professional & scientific | 2025 |
| Simon Ashby Studios Limited | Arts & recreation | 2002 |
| Simon Bahia Optics Limited | Wholesale & retail | 2023 |
| Simon Bennett Civils Limited | Extraterritorial | 2017 |
| Simon Giles Turnbull Limited | Extraterritorial | 2024 |
| Simple Projects Limited | Information & communication | 2010 |
| Simple Steps Training C.I.C. | Education | 2021 |
| Simplifi Technologies Limited | Extraterritorial | 2005 |
| Simply Advanced Practice Ltd | Health & social care | 2022 |
| Simply Commercial Ltd | Financial services | 2011 |
| Simply Delicious (Aldridge) Limited | Hospitality | 2007 |
| Simply Renovations Limited | Construction | 2024 |
| Simply Shred & Recycle Limited | Professional & scientific | 2008 |
| Simply Shred Limited | Water & waste | 2005 |
| Simply Staff Limited | Administrative & support | 2018 |
| Simply Supervision Ltd | Education | 2025 |
| Simply Takafal Holdings Limited | Financial services | 2026 |
| Simply Takafal Ltd | Public administration | 2026 |
| Simplyola Beauty Fashion and Accessories Limited | Wholesale & retail | 2020 |
| Simran Empire Limited | Real estate | 2024 |
| Sing Away CIC | Arts & recreation | 2021 |
| Singh Acupressure Treatment Limited | Health & social care | 2021 |
| Singh Carpets & Flooring Ltd | Construction | 2025 |
| Singh Equipment Rental Limited | Administrative & support | 2025 |
| Singh IT Consulting Limited | Professional & scientific | 2014 |
| Sinti & Co Ltd | Hospitality | 2024 |
| SIP & Savour PUB Co Ltd | Hospitality | 2024 |
| Sipahi Limited | Households | 2025 |
| SIR Security Systems Limited | Administrative & support | 2016 |
| Sircar Medical Limited | Health & social care | 2021 |
| Sirdarji Couriers Limited | Transport & logistics | 2022 |
| Sirethi Mango Company Limited | Health & social care | 2018 |
| SIS IT Consult Limited | Information & communication | 2015 |
| Site Secured Limited | Administrative & support | 2010 |
| Sitewatch Limited | Administrative & support | 2014 |
| Sith Happens Ltd | Hospitality | 2021 |
| SIX Ways Secretaries Limited | Professional & scientific | 1996 |
| SIXTY3 Property Limited | Real estate | 2023 |
| SJ Auto Ltd | Wholesale & retail | 2024 |
| SJ Mobiles PVT Ltd | Wholesale & retail | 2021 |
| SJ Security Solutions & K9 Ltd | Administrative & support | 2023 |
| SJA Worldwide Ltd | Wholesale & retail | 2021 |
| SJC Contracts Ltd | Construction | 2022 |
| SJD 2026 Ltd | Arts & recreation | 2026 |
| SJD Interiors Ltd | Wholesale & retail | 2018 |
| SJH Interim Accountancy Limited | Professional & scientific | 2024 |
| SJL Assets Ltd | Professional & scientific | 2020 |
| SJM Solutions Limited | Professional & scientific | 2020 |
| SJP Telecoms Consultants Ltd | Information & communication | 2024 |
| SJS Landscaping Limited | Administrative & support | 2026 |
| SK 94 Ltd | Professional & scientific | 2025 |
| SK Boutique Limited | Wholesale & retail | 2025 |
| SK Choice Limited | Wholesale & retail | 2024 |
| SK Dhan Consultants Limited | Health & social care | 2026 |
| SK Foods Group Ltd | Hospitality | 2024 |
| SK Retail Ltd | Real estate | 2015 |
| SK Sport Assets Limited | Wholesale & retail | 2010 |
| SK Tuning Ltd | Wholesale & retail | 2019 |
| SK Velvet Touch Ltd | Other services | 2026 |
| Sk&M ENT Limited | Health & social care | 2025 |
| SKA Pharma Ltd | Public administration | 2025 |
| Skalle Ltd | Transport & logistics | 2024 |
| Skat-Uk Limited | Wholesale & retail | 2019 |
| SKB Commercial Engineering Ltd | Professional & scientific | 2021 |
| Skel Limited | Professional & scientific | 2021 |
| Skelkon Ltd | Other services | 2021 |
| Skelson UK Limited | Transport & logistics | 2023 |
| SKG Investments Limited | Real estate | 2012 |
| SKI Franchise Ltd | Professional & scientific | 2023 |