| SLW Instrumentation Limited | Construction | 2025 |
| SM Access Limited | Construction | 2014 |
| SM Electrical (NE) Limited | Construction | 2026 |
| SM OPS Limited | Water & waste | 2026 |
| SM Rope Access Ltd | Professional & scientific | 2025 |
| Small Sided Football Club Ltd | Education | 2020 |
| Smart Edge CIC | Information & communication | 2025 |
| Smart London Properties UK Ltd | Real estate | 2019 |
| Smart Property Systems Ltd | Households | 2026 |
| Smart System Solutions Ltd | Other services | 2022 |
| Smartify ME Ltd | Construction | 2017 |
| Smartseal Roads Ltd | Construction | 2025 |
| Smarty Commerce Ltd | Wholesale & retail | 2026 |
| Smashfactor Limited | Other services | 2024 |
| SMB Training Ltd | Education | 2016 |
| SMC Loler Services Ltd | Construction | 2024 |
| SMG Tech Services Limited | Construction | 2019 |
| Smith Hogg & Company Limited | Real estate | 1922 |
| Smith UK Group Limited | Financial services | 2021 |
| Smith UK Property Limited | Real estate | 2018 |
| Smith UK Renovation Limited | Construction | 2019 |
| Smith's Children's Wear Limited | Wholesale & retail | 2025 |
| Smiths Pilotage & Consultancy Limited | Transport & logistics | 2012 |
| Smlf Ltd | Water & waste | 2013 |
| Smokedhartlepool Ltd | Hospitality | 2026 |
| Smooth Vapourz Ltd | Wholesale & retail | 2014 |
| SMS Holdings NW Ltd | Real estate | 2019 |
| SMT Consulting Ltd | Professional & scientific | 2024 |
| SMT Limited | Construction | 2023 |
| Smurf Designs Ltd | Professional & scientific | 2023 |
| Snacky Vending Ltd | Hospitality | 2026 |
| SO Easy Seasonings Ltd | Wholesale & retail | 2018 |
| Social Property Ventures Limited | Financial services | 2022 |
| Solaccom Ltd | Hospitality | 2026 |
| Solar Panels and Exterior Washing Limited | Administrative & support | 2026 |
| Solid Oak Hardwood Furniture (Southern) Limited | Manufacturing | 2015 |
| Solutions Joinery Limited | Construction | 2016 |
| Solutions-Injection Moulding Limited | Manufacturing | 2003 |
| Something Positive Solutions Community Interest Company | Health & social care | 2019 |
| Sonder Santiago Ltd. | Real estate | 2023 |
| Sonice City Limited | Wholesale & retail | 2026 |
| Sophie's Enterprise Limited | Professional & scientific | 2013 |
| Sorrento Pizzeria Limited | Hospitality | 2024 |
| Soul Properties Rentals and Renovations Ltd | Real estate | 2024 |
| Souls, Imagination Village Ltd | Arts & recreation | 2025 |
| South Shore One Limited | Real estate | 2004 |
| Sovereign Souls Ltd | Health & social care | 2025 |
| SP Alloys Ltd | Wholesale & retail | 2026 |
| SP Holding (NE) Co Limited | Financial services | 2026 |
| Spa Engineering Solutions North East Ltd | Construction | 2023 |
| Spark Creative Design Limited | Information & communication | 2006 |
| Sparkicus Ltd | Construction | 2026 |
| Sparkles N Clean Ltd | Administrative & support | 2024 |
| Spartacus Commercial Ltd | Real estate | 2025 |
| Spartacus FAB Ltd | Manufacturing | 2023 |
| Spaven Art Ltd | Administrative & support | 2016 |
| Special Cleaning Limited | Administrative & support | 2019 |
| Sphere Developments Ltd | Real estate | 2020 |
| SPI Electrical Ltd | Construction | 2015 |
| Spicy HUT Hartlepool Limited | Hospitality | 2025 |
| Sping (NE) Limited | Administrative & support | 2020 |
| Spire Financial Management Limited | Financial services | 2002 |
| Sports Management International Ltd. | Arts & recreation | 1993 |
| Spotless Auto Repairs and Service Limited | Wholesale & retail | 2026 |
| Spreadfast Limited | Construction | 2010 |
| Springwell Developments (Seamer) Limited | Construction | 2023 |
| Springwell Electrical Ltd | Construction | 2022 |
| Spudgun Events Ltd | Hospitality | 2024 |
| SPZ Limited | Professional & scientific | 2015 |
| SRA Products Ltd | Wholesale & retail | 2019 |
| SRB Fibre Limited | Construction | 2025 |
| SRB Plumbing & Mechanical Services Ltd | Construction | 2017 |
| SRB Services UK Ltd | Manufacturing | 2009 |
| SRJ Convenience Limited | Wholesale & retail | 2018 |
| SRO Trading Ltd | Wholesale & retail | 2021 |
| SS Cables Ltd | Construction | 2021 |
| SS Logistics 2000 Ltd | Real estate | 2017 |
| Ss-Et Ltd | Professional & scientific | 2020 |
| SSM Inspection Services Ltd | Professional & scientific | 2025 |
| SSS Fire and Security Ltd | Administrative & support | 2017 |
| ST Aidans Apartments Management Ltd | Extraterritorial | 2011 |
| ST Andrews Park (Vine Lane 1A) Management Company Limited | Households | 2014 |
| ST Andrews Smart Homes Ltd | Financial services | 2025 |
| ST Tandoori Ltd | Hospitality | 2023 |
| Stag Competitions Limited | Arts & recreation | 2025 |
| Stand by ME Enterprises Ltd | Health & social care | 2025 |
| Starfish Health and Well-Being Community Interest Company | Health & social care | 2009 |
| Starfish Services Limited | Extraterritorial | 2009 |
| Stars Community Learning CIC | Education | 2022 |
| Staunch Property Limited | Real estate | 2019 |
| Stax Property Rentals Ltd | Real estate | 2026 |
| Steelspirit Limited | Professional & scientific | 2023 |
| Stekev Limited | Construction | 2018 |
| Stephen Makinson Limited | Administrative & support | 2019 |
| Stephenson’S Leisure Limited | Hospitality | 2020 |
| Steron Locksmiths Limited | Other services | 2014 |
| Stevenson Group (N.E.) Limited | Extraterritorial | 2022 |
| Stevenson Renewables Limited | Real estate | 2014 |
| Sticky Interior Ltd | Wholesale & retail | 2026 |
| Stockton Accident Repair Centre Limited | Extraterritorial | 2024 |