| Solos Shomax Ltd | Energy | 2021 |
| Solstice Zone a Management Company Limited | Real estate | 2006 |
| Somerset BNG Limited | Construction | 2025 |
| Somerset Landscapes Limited | Administrative & support | 1993 |
| Somerset Nutter Ltd | Households | 2026 |
| Somerset Parent Carer Forum C.I.C. | Information & communication | 2016 |
| Somerset Plant and Groundworks Limited | Wholesale & retail | 2021 |
| Somerset Primary Healthcare Limited | Health & social care | 2013 |
| Somerset Stays Limited | Real estate | 2024 |
| Somerset Stays Management Limited | Administrative & support | 2025 |
| Somerset Tattoo Convention Ltd | Arts & recreation | 2025 |
| Somerton Environmental Ltd | Professional & scientific | 2016 |
| Sonam Health Care Ltd | Health & social care | 2018 |
| Sonder & Meraki Ltd | Professional & scientific | 2021 |
| Sonni's Cafe Limited | Hospitality | 2018 |
| Sophia Trans Ltd | Transport & logistics | 2025 |
| Sophie Ashby Limited | Professional & scientific | 2018 |
| SOS Autolocks Limited | Other services | 2008 |
| Sound Thinking Ltd | Education | 2011 |
| South Somerset Vans Ltd | Wholesale & retail | 2024 |
| South Street Trading Ltd | Real estate | 2024 |
| South Street WIN Ltd | Households | 2022 |
| South West Audio Yeovil Limited | Hospitality | 2022 |
| South West Main Line Steam Company | Arts & recreation | 1994 |
| South West Pumps Limited | Construction | 2009 |
| South West Reindeer Ltd | Agriculture & fishing | 2018 |
| South West Services CG Ltd | Transport & logistics | 2004 |
| Southern Counties Heating Solutions Ltd | Construction | 2022 |
| Southern Live in Carers Limited | Administrative & support | 2021 |
| Southwest Property Clearance Limited | Water & waste | 2025 |
| Southwest Signature Limited | Information & communication | 2017 |
| Southwoods Dental Practice Limited | Health & social care | 2009 |
| Souvlaki.Gr Ltd | Hospitality | 2020 |
| SP8 Cleaners Limited | Administrative & support | 2019 |
| Space Vault Limited | Transport & logistics | 2018 |
| Sparkford Management Company Limited | Real estate | 2004 |
| Sparkford Storage Limited | Transport & logistics | 2016 |
| Sparkles Shop Limited | Wholesale & retail | 2025 |
| Sparrow & Newman Ltd | Extraterritorial | 1971 |
| Spectre Building Solutions Limited | Construction | 2017 |
| Spencer Emmett Services Ltd | Manufacturing | 2023 |
| Spices Roots Ltd | Wholesale & retail | 2025 |
| Spirit Gymnastics Academy Limited | Education | 2018 |
| Spirit Interco Limited | Financial services | 2021 |
| Spirit Property Investment Limited | Real estate | 2017 |
| Springhead Constellation Ltd | Arts & recreation | 2024 |
| Sprydon Homes Ltd | Real estate | 2025 |
| SR Window & External Cleaning Specialists Ltd | Administrative & support | 2024 |
| SSD Petroleum Limited | Wholesale & retail | 2024 |
| Ssdc Opium Power Limited | Energy | 2018 |
| SST Homes Limited | Real estate | 2024 |
| SST Petroleum Limited | Wholesale & retail | 2020 |
| ST Gerorge for Medical Services Limited | Health & social care | 2025 |
| ST. James's Place (Dorchester) Management Co. Ltd | Households | 2003 |
| ST. Matthews Court Management Company Limited | Real estate | 1976 |
| ST. Michael's Academy | Education | 2012 |
| ST. Michaels Court Management (Yeovil) Limited | Hospitality | 2004 |
| ST. Pauls (Wincanton) RTM Company Limited | Households | 2016 |
| ST. Peters (Wincanton) RTM Company Limited | Households | 2016 |
| Staddons Ltd | Professional & scientific | 2015 |
| Stan Bathrooms Ltd | Construction | 2023 |
| Standon Lordship Limited | Professional & scientific | 2005 |
| Stanhope Research and Development Limited | Professional & scientific | 2013 |
| Star Child (Glastonbury) Limited | Wholesale & retail | 2003 |
| Star ED Takeaway Ltd | Hospitality | 2025 |
| Start Smart Children’S Clothing UK Limited | Wholesale & retail | 2023 |
| Stayner-Robertson Inns Limited | Hospitality | 2018 |
| Stead Capital Investments Ltd | Financial services | 2025 |
| Step by Step Cleaning Services Ltd | Administrative & support | 2020 |
| Step by Step Commercial Cleaning Solutions Ltd | Administrative & support | 2022 |
| Sterling Technical Services (Malvern) Limited | Professional & scientific | 2017 |
| Sterling Technical Services Limited | Professional & scientific | 2006 |
| Steve Paul Ltd | Agriculture & fishing | 2006 |
| Steve Randall Carpentry Ltd | Construction | 2024 |
| Stewies Limited | Transport & logistics | 2024 |
| Stiby Road (Yeovil) Management Company Limited | Households | 1989 |
| Stimpson Properties Ltd | Real estate | 2024 |
| Stirling Sheq Consultancy Ltd | Professional & scientific | 2025 |
| Stochastic Rustacean Limited | Information & communication | 2024 |
| Stoford Investment Property Limited | Real estate | 2018 |
| Stoic Trading Limited | Financial services | 2014 |
| Stokes Retail Ltd | Wholesale & retail | 2023 |
| Stone Farm Barns Management Company Limited | Households | 2020 |
| Stone PIT Construction Ltd | Construction | 2014 |
| Stoneybrook Limited | Hospitality | 2014 |
| STOP2QUENCH Ltd | Hospitality | 2024 |
| STQ Vantage Limited | Construction | 2019 |
| Strategy One Limited | Professional & scientific | 2022 |
| Strathview Limited | Construction | 1982 |
| Stratland Hicks Gate Limited | Real estate | 2014 |
| Stride Accountancy Limited | Professional & scientific | 2026 |
| Stroppy COW Properties Ltd | Real estate | 2011 |
| STS (Yeovil) Ltd | Manufacturing | 2004 |
| Stuart Foster Funeral Services Ltd | Other services | 2017 |
| Studio 23 Pilates Ltd | Arts & recreation | 2020 |
| Studio Ashby Holdings Limited | Financial services | 2024 |
| Studio Ashby International Limited | Professional & scientific | 2022 |
| Studio Ashby Limited | Professional & scientific | 2013 |
| Studio TF1 Ltd | Information & communication | 2022 |
| Studio TRW Ltd | Information & communication | 2025 |