| Senior Heating Services Ltd | Construction | 2023 |
| Senior Heating Solutions Ltd | Construction | 2026 |
| Sennen Cliff Ltd | Real estate | 2019 |
| Sense Interact Limited | Information & communication | 2014 |
| Serenescapes Landscaping Ltd | Administrative & support | 2023 |
| Serenity Stoves Limited | Construction | 2025 |
| Serenlight Limited | Professional & scientific | 2008 |
| Sertay Limited | Hospitality | 2015 |
| Seven DOT Energy Limited | Professional & scientific | 2015 |
| Seven Harbour View RTM Co. Ltd. | Households | 2011 |
| Seven Oak Consulting Ltd | Administrative & support | 2018 |
| Seven Sisters Socials Limited | Information & communication | 2023 |
| Seventh Seal Limited | Wholesale & retail | 2016 |
| Seventy Four by Matt Ltd | Hospitality | 2024 |
| SEVENTY9 Investments Limited | Hospitality | 2017 |
| Seymour House Partners Limited | Real estate | 2026 |
| SG Wellness Developments Limited | Wholesale & retail | 2021 |
| SGM Hair Salons Limited | Other services | 2010 |
| Shaan Ventures Limited | Other services | 2025 |
| Shabbat Shalom Care Limited | Health & social care | 2013 |
| Shamseldin Medical Ltd | Health & social care | 2021 |
| Shapla Trading Ltd | Hospitality | 2025 |
| Sharaun Limited | Transport & logistics | 2019 |
| Sharnhill Green Storage Ltd | Transport & logistics | 2024 |
| Shauna Care Angels Limited | Public administration | 2025 |
| Shauna Health Care Service Solutions Limited | Health & social care | 2018 |
| Shepherds Walk Management Ltd | Households | 2020 |
| Sherilyn King Limited | Agriculture & fishing | 1978 |
| Sherrings Green Close Management Company Limited | Professional & scientific | 2008 |
| Sherrins Farm Management Company Limited | Real estate | 2017 |
| Shield Corporate Finance Ltd. | Financial services | 1999 |
| SHONA1 Limited | Professional & scientific | 2026 |
| Shore Wave Ltd | Construction | 2022 |
| Shoreline Building Ltd | Construction | 2023 |
| Shoreline Building Projects Ltd | Construction | 2009 |
| Shoreline Surveys Limited | Professional & scientific | 2002 |
| Shoshin Limited | Professional & scientific | 2001 |
| Showcase Events Limited | Extraterritorial | 2025 |
| Sias Properties LLP | | 2007 |
| Side by Side Companionship Ltd | Health & social care | 2026 |
| Siegel & Stockman (UK) Limited | Wholesale & retail | 1999 |
| Sienna UK Limited | Professional & scientific | 2008 |
| Sienoma Investments Ltd | Financial services | 2025 |
| Sienoma Ltd | Real estate | 2021 |
| Silicone Hygiene Ltd | Manufacturing | 2021 |
| Silver Horse Antiques Limited | Wholesale & retail | 2012 |
| Silver Links Coaching and Consulting Ltd | Professional & scientific | 2022 |
| Simjet Aviation Limited | Administrative & support | 2011 |
| Simon Ledger Limited | Other services | 2010 |
| Simon Thomas Studios Limited | Professional & scientific | 2021 |
| Simply Bathrooms & Bedrooms of Sherborne Limited | Construction | 2014 |
| Simpson Creative Limited | Wholesale & retail | 2000 |
| Simpson Farming Ltd | Agriculture & fishing | 2014 |
| Siri G Consulting Ltd | Professional & scientific | 2007 |
| Site Developments (Ferndown) Limited | Construction | 1966 |
| SIX Harbour View Limited | Households | 2008 |
| SIX Oaks Home Care Ltd | Health & social care | 2020 |
| SJ Dorset Residential Limited | Real estate | 2024 |
| SJ Flavours Ltd | Hospitality | 2024 |
| SJ Pyle Consulting Limited | Education | 2016 |
| Skin Deep (Dorset) Limited | Transport & logistics | 2022 |
| Skippetts Farm Limited | Professional & scientific | 1962 |
| Skybound Innovations Ltd | Professional & scientific | 2016 |
| Skyline Bookbinders Limited | Extraterritorial | 2007 |
| Skyschool Flight Centre Limited | Arts & recreation | 2006 |
| Slade Consulting Limited | Construction | 2000 |
| SLC Property Investments Limited | Construction | 2016 |
| SLR Property Lettings Ltd | Real estate | 2025 |
| SM Grid Consulting Ltd | Administrative & support | 2023 |
| Smaikssme Ltd | Arts & recreation | 2018 |
| Smalldog Ltd | Information & communication | 2015 |
| Smarla Limited | Health & social care | 2024 |
| Smart Cyber Group Limited | Professional & scientific | 2020 |
| Smart Home Improvements Dorset Ltd | Construction | 2015 |
| Smart Lettings Dorset Limited | Real estate | 2021 |
| Smcc (UK) Limited | Construction | 2014 |
| Smileydaze Limited | Administrative & support | 2004 |
| Sminky Limited | Health & social care | 2018 |
| Smith's Cleaning of Dorset Ltd | Administrative & support | 2026 |
| Smith's Marine Services Ltd | Administrative & support | 2024 |
| SMX Medical Limited | Other services | 2024 |
| Snashall Steel Fabrications Company Limited | Manufacturing | 1975 |
| Snedsreve Sytreporp Limited | Agriculture & fishing | 1975 |
| Soakvale Ltd | Construction | 2010 |
| Social Hippo Ltd | Professional & scientific | 2024 |
| Socomore Ltd. | Wholesale & retail | 2000 |
| Sofie Jeanne Alice Collette Limited | Extraterritorial | 2023 |
| Soft Shoe Films Ltd | Administrative & support | 2021 |
| SOG (Yeovil) Ltd | Other services | 2018 |
| Soho Drinks Limited | Professional & scientific | 2025 |
| Solace Training UK Limited | Education | 2026 |
| Solitaire Gold Ltd | Wholesale & retail | 2024 |
| Solo IT Consulting Ltd | Professional & scientific | 2024 |
| Solomons Family Property (Bournemouth) Ltd. | Real estate | 2013 |
| SOLUTIONS4DAMP Limited | Construction | 2023 |
| Somer Health & Strength Club | Arts & recreation | 2019 |
| Somerset (Weymouth) Management Limited | Households | 2011 |
| Somerset Motors (Yeovil) Limited | Professional & scientific | 1952 |
| Somnisense Limited | Information & communication | 2026 |
| Sonix Developments Limited | Real estate | 2015 |