| Skin & Sole Clinic Ltd | Health & social care | 2026 |
| Skip-Rite Limited | Water & waste | 2016 |
| SKL Converting Hydraulics Division Limited | Wholesale & retail | 2024 |
| SKL Converting Limited | Wholesale & retail | 2014 |
| SKS Workshop Ltd | Professional & scientific | 2024 |
| Sky Sense Aviation Limited | Professional & scientific | 2023 |
| SLA Survey Limited | Professional & scientific | 2017 |
| Slim Diggings Ltd | Construction | 2023 |
| Slipstream Optics Ltd | Extraterritorial | 2022 |
| SLT Companions Ltd | Health & social care | 2026 |
| SLX Clements Ltd | Professional & scientific | 2022 |
| SLX Group Limited | Wholesale & retail | 1935 |
| SLX Logistics Limited | Transport & logistics | 2023 |
| SLX Renewables Limited | Transport & logistics | 2023 |
| Small Business PCS Limited | Information & communication | 2010 |
| Smart River Limited | Professional & scientific | 2020 |
| Smart Staff Recruitment Limited | Transport & logistics | 2018 |
| Smartair Technologies Ltd | Manufacturing | 2025 |
| Smartbuild General Builders Ltd | Construction | 2023 |
| Smartcybersecurity Ltd | Information & communication | 2017 |
| SMD Carpentry and Construction Ltd | Construction | 2025 |
| Smile Circle PVT Ltd | Health & social care | 2022 |
| Smith & Sons Structural Ltd | Construction | 2014 |
| Smith and Clarks Limited | Wholesale & retail | 2019 |
| Smith Aviation Limited | Other services | 2017 |
| Smith's Hearing Care Limited | Health & social care | 2018 |
| Smiwell Limited | Professional & scientific | 2025 |
| SML Holdings Group Limited | Financial services | 2023 |
| SML Supplies Limited | Wholesale & retail | 1998 |
| SMP Snak Products Ltd | Manufacturing | 2018 |
| Smrs Fabrications and Welding Ltd | Manufacturing | 2015 |
| Snack Bite Ltd | Hospitality | 2024 |
| Snazzy Bikes UK Ltd | Manufacturing | 2021 |
| SNM Aerial Ltd | Information & communication | 2024 |
| Snow FOX Ltd | Wholesale & retail | 2020 |
| SNS Building Products Limited | Wholesale & retail | 2012 |
| SO Recycle Ltd | Water & waste | 2017 |
| Socks GOT Sole Limited | Wholesale & retail | 2023 |
| Software Recruitment Solutions Limited | Other services | 2020 |
| SOL Flame Ltd | Hospitality | 2025 |
| Solstice Soft Play Limited | Arts & recreation | 2015 |
| Somerset Kent Ltd | Wholesale & retail | 2020 |
| SON Vida Developments Limited | Financial services | 2023 |
| Sonar Electrical&Controls Ltd | Construction | 2017 |
| Sonnies Landscapes Ltd | Administrative & support | 2025 |
| Sophia Communications Limited | Information & communication | 2020 |
| Soul Helper Limited | Other services | 2025 |
| Soulfri Ltd | Hospitality | 2024 |
| Sound Decisions Limited | Wholesale & retail | 2000 |
| Sourcex Executive Ltd | Administrative & support | 2025 |
| South America REP Limited | Professional & scientific | 2018 |
| South Surveying Services Limited | Construction | 2005 |
| South West Health and Safety Training Limited | Education | 2016 |
| South Wilts Archery Club Limited | Arts & recreation | 2009 |
| Southern Best Honey Ltd | Other services | 2019 |
| Southern Camper Care Limited | Manufacturing | 2018 |
| Southern EV Installations Ltd | Construction | 2025 |
| Southern Installation Solutions Limited | Construction | 2013 |
| Southern Sewing Machine Ltd | Manufacturing | 2021 |
| Southern Solar Systems Ltd | Construction | 2025 |
| Southpaw Software Limited | Information & communication | 2019 |
| Southwood Rail Consulting Limited | Transport & logistics | 2016 |
| Sovereign Insights Ltd | Information & communication | 2025 |
| SP Electrical Contracting Ltd | Construction | 2016 |
| Sp-Builders (South) Limited | Construction | 2022 |
| Space Newt Studios Ltd | Information & communication | 2024 |
| Spaniel Companions Ltd | Agriculture & fishing | 2025 |
| Spanish Pottery Ltd | Wholesale & retail | 2022 |
| Sparking Ideas Limited | Information & communication | 2011 |
| Sparks Rentals Ltd | Real estate | 2021 |
| Spatex Limited | Professional & scientific | 1996 |
| Spear Design Projects Ltd | Construction | 2002 |
| Spear Electrical Limited | Construction | 1999 |
| Spear Fire & Security Limited | Construction | 2011 |
| Spear Technical Group Ltd | Financial services | 2012 |
| Specialist Seating Solutions Ltd | Manufacturing | 2024 |
| Specialist Shading Limited | Professional & scientific | 2024 |
| Spectrum IT Training Services Limited | Information & communication | 2006 |
| Speculate Developments Limited | Real estate | 2007 |
| Speedy GON Ltd | Transport & logistics | 2023 |
| Spencer House (Freehold) Limited | Households | 1996 |
| Spencer Solutions Limited | Financial services | 2013 |
| Spice Andover Limited | Hospitality | 2024 |
| Spices and Spirits Restaurants Ltd | Hospitality | 2024 |
| Sports & Touring Ltd | Wholesale & retail | 2019 |
| Sporty Bees Ltd | Education | 2025 |
| Sprat and Winkle Limited | Other services | 2014 |
| Spruce Resources Limited | Wholesale & retail | 2021 |
| Spyce Route Andover Limited | Hospitality | 2023 |
| Spyce Route Takeaway Limited | Hospitality | 2023 |
| Spyke Digital Ltd | Professional & scientific | 2010 |
| Square Foot Self Storage Limited | Real estate | 2007 |
| SS Plumbing & Mechanical Ltd | Construction | 2021 |
| Ssah Ltd | Hospitality | 2024 |
| SSE Building Ltd | Construction | 2021 |
| ST Mary Bourne Garage Limited | Wholesale & retail | 2003 |
| ST. Mellons Country Estates Limited | Real estate | 1935 |
| Stama Ltd | Transport & logistics | 2016 |
| Stamford Court Andover Management Limited | Households | 2020 |
| Stannah Homelifts Limited | Manufacturing | 1984 |