| Socktopus Media Ltd | Professional & scientific | 2019 |
| Softchase Ltd | Real estate | 1997 |
| Software-Matters (Software Solutions) Ltd | Information & communication | 2016 |
| Solaise Southern Limited | Real estate | 2015 |
| Solartile Limited | Extraterritorial | 2000 |
| Solex Energy Ltd | Manufacturing | 2001 |
| Solo Plumbing, GAS & Electrical Limited | Construction | 2015 |
| Solside Limited | Real estate | 1987 |
| Solus IT Business Solutions Limited | Information & communication | 2009 |
| Somerset Welding Ltd | Administrative & support | 2020 |
| Sophies Pink Palace Ltd | Hospitality | 2025 |
| Soteria Health and Safety Limited | Professional & scientific | 2016 |
| SOU West Lodge Hotel Limited | Hospitality | 2021 |
| South Coast Alarms Ltd | Construction | 2000 |
| South Coast Bespoke Interiors Ltd | Construction | 2025 |
| South Coast Clay Shooting Ltd | Arts & recreation | 2023 |
| South Coast Garden Machinery Ltd | Wholesale & retail | 2008 |
| South Coast Precision Limited | Manufacturing | 2021 |
| South Coast Spray Rendering Limited | Construction | 2016 |
| South Dorset Electrical Services Ltd | Manufacturing | 2011 |
| South Dorset Plumbing & Heating Ltd | Construction | 2023 |
| South Seas Vanilla LLP | | 2019 |
| South West Cake Company Ltd | Manufacturing | 2026 |
| South West Signs (Sherborne) Limited | Administrative & support | 2006 |
| Southbrook (2003) Management Limited | Real estate | 2003 |
| Southcoast Tiling Ltd | Construction | 2022 |
| Southdene Court Management Company Limited | Households | 1982 |
| Southern Counties Resins Limited | Construction | 2025 |
| Southern County Marine Ltd | Transport & logistics | 2016 |
| Southern Cygnet Swim School Ltd | Other services | 2013 |
| Southern Fresh Seafood Ltd | Wholesale & retail | 2019 |
| Southern Ice Company Limited | Administrative & support | 2007 |
| Sovereign Mill Morley Leasehold 57 Ltd | Real estate | 2025 |
| Space, LAB Studio Ltd | Education | 2025 |
| Sparrow Holdings Dorset Ltd | Real estate | 2026 |
| Specialist Sub-Sea Engineering (Offshore) Ltd | Professional & scientific | 2010 |
| Spellman Limited | Hospitality | 2020 |
| Sphere Electrical Limited | Construction | 2003 |
| Spinnaker View Management Company Limited | Real estate | 2001 |
| Spirit UP Coffee Ltd | Hospitality | 2026 |
| Splashtogether Ltd | Education | 2020 |
| SPP Fine Finishes Ltd | Construction | 2013 |
| SPP Group Holdings Limited | Financial services | 2022 |
| Sprida Ltd | Professional & scientific | 2018 |
| Spring Tides Weymouth Ltd | Real estate | 2022 |
| Spvwfreehold Ltd | Households | 2021 |
| Squibb & Taylor (South West) Limited | Construction | 2011 |
| SR Property & Compliance Services Ltd | Construction | 2024 |
| Srinikasri Limited | Wholesale & retail | 2018 |
| Srinikasrii Limited | Wholesale & retail | 2023 |
| Srji Commercial Ltd | Real estate | 2024 |
| SSO Investments Ltd | Financial services | 2023 |
| ST Annes Holiday Cottages Limited | Administrative & support | 2000 |
| ST Jude's Care (Dorchester) Limited | Health & social care | 2021 |
| ST Jude's Care Holding Ltd | Financial services | 2020 |
| ST Jude's Care Ltd | Health & social care | 2007 |
| Stagestore Ltd | Arts & recreation | 2024 |
| Stallard Travel and Tours Ltd | Transport & logistics | 2025 |
| Stamper Lets Limited | Real estate | 2018 |
| Stanbridge and Crichel (Poole) Limited | Professional & scientific | 1989 |
| Station Approach (Brock) Ltd | Water & waste | 2023 |
| Statue Property Insurance Services Limited | Financial services | 2003 |
| Stauner Health Informatics Ltd | Professional & scientific | 2025 |
| Stavordale Court Company Limited | Households | 1973 |
| Steelhawk MC Limited | Arts & recreation | 2018 |
| Stephen Chang Associates Limited | Information & communication | 1996 |
| Stephen Daws Ltd | Information & communication | 2013 |
| Steppes Sand Company Limited | Professional & scientific | 1959 |
| Steve Smith (Building Contractors) Limited | Construction | 2000 |
| Steve Staple Ltd | Real estate | 2025 |
| Steven Flann Building Services Limited | Construction | 2003 |
| Stick Giraffe Property Management Ltd | Real estate | 2018 |
| Stickland & Sons Ltd | Agriculture & fishing | 2026 |
| Stika.Co Ltd | Manufacturing | 2014 |
| STJ Civils Ltd | Construction | 2023 |
| Stockley Motors LLP | | 2004 |
| Stone Firms (UK) Limited | Extraterritorial | 2010 |
| Stone Firms Limited | Mining & quarrying | 2004 |
| Stone Hooper Ltd | Construction | 2020 |
| Stone Pier Cafe Ltd | Hospitality | 2019 |
| Stone Valley West Country Ltd | Wholesale & retail | 2019 |
| Stormchild Ventures Ltd | Information & communication | 2009 |
| Stour Road Stores Limited | Wholesale & retail | 2016 |
| Stourcliffe Supported Living Ltd | Health & social care | 2010 |
| Stracey's Fish and Chips Limited | Hospitality | 2022 |
| Stuart Barnes Limited | Construction | 2001 |
| Stuart Wiltshire Glass Limited | Manufacturing | 2009 |
| Studio Hannan Ltd | Real estate | 2025 |
| Studio Krooks Ltd | Construction | 2022 |
| Studiobeam Productions Ltd | Arts & recreation | 2020 |
| Sturminster Newton Amateur Boxing Club Community Interest Company | Arts & recreation | 2009 |
| Stylish Stitches LLP | | 2002 |
| Subhaan Enterprise Ltd | Wholesale & retail | 2019 |
| Suleyman Alak Catering Ltd | Transport & logistics | 2022 |
| Sumac Manufacturing (Holdings) Limited | Financial services | 2019 |
| Sumac Precision Engineering Limited | Professional & scientific | 1995 |
| Summer Holdings Dorset Limited | Real estate | 2025 |
| Summer Psychology Services Limited | Health & social care | 2022 |
| Sunflowers Floral Design Limited | Wholesale & retail | 2002 |
| Sunny Days Broadstone Limited | Education | 2014 |