| Sealey Equine Limited | Agriculture & fishing | 2025 |
| Serenity (South) Limited | Construction | 2024 |
| Servergodz Ltd | Wholesale & retail | 2026 |
| Service Appliances Limited | Wholesale & retail | 2002 |
| Sesantipay Ltd | Professional & scientific | 2022 |
| Seymer Close Limited | Professional & scientific | 2003 |
| Shambrook Cardiothoracic Imaging Limited | Health & social care | 2024 |
| Shapwick Community Trust Limited | Arts & recreation | 2003 |
| Sherborne Arts Trust | Arts & recreation | 2009 |
| Shibui ILK Ltd | Agriculture & fishing | 2020 |
| Shingford Roofing Ltd | Construction | 2024 |
| Shorewood Interiors Ltd | Construction | 2026 |
| Shroton Fair GIN Ltd | Manufacturing | 2021 |
| Sigmacrest Limited | Professional & scientific | 1980 |
| Silvertooth Investments Limited | Administrative & support | 2002 |
| Simla Blandford Limited | Hospitality | 2016 |
| Simon Thomas Pirie Limited | Manufacturing | 2007 |
| Simply a PUB Ltd | Hospitality | 2024 |
| Sindrome Limited | Arts & recreation | 2023 |
| Sister Art Limited | Wholesale & retail | 2019 |
| SJL Fishing Limited | Agriculture & fishing | 1999 |
| SJW Forestry Ltd | Agriculture & fishing | 2013 |
| SK Picture Framing Ltd | Wholesale & retail | 2023 |
| SKC Limited | Manufacturing | 1982 |
| SLA IT Services Ltd | Information & communication | 2026 |
| Slade&Co (UK) Ltd | Professional & scientific | 2016 |
| Slime Mania Ltd | Wholesale & retail | 2020 |
| Smartgrid Energy Infrastructure Ltd | Construction | 2026 |
| SNJ Contracting Ltd | Agriculture & fishing | 2011 |
| Social Heights Ltd | Professional & scientific | 2024 |
| Solec Limited | Construction | 2005 |
| Sonny Ltd | Transport & logistics | 2024 |
| Sophie Ceramics (Wimborne) Ltd | Construction | 2026 |
| Sophie’S Ceramics Ltd | Construction | 2022 |
| South Close Management Limited | Households | 1991 |
| South Coast Customs & Classics Ltd | Wholesale & retail | 2014 |
| South Coast Electrical Solutions Ltd | Construction | 2018 |
| South Coast Guttering & Roofing Services Ltd | Construction | 2024 |
| South Coast Mussels Limited | Agriculture & fishing | 1996 |
| South Coast Survey Ltd | Professional & scientific | 2026 |
| South Paddocks Limited | Agriculture & fishing | 2020 |
| Southampton CTS Limited | Health & social care | 2010 |
| Southern Appliance Services Ltd | Other services | 2003 |
| Southern Cross Electrical Services Ltd | Construction | 2017 |
| Southern Cross Solar Ltd | Construction | 2023 |
| Southern Window Cleaning Services Limited | Administrative & support | 2024 |
| SP Insights Ltd | Information & communication | 2017 |
| Spark Bloom Ltd | Information & communication | 2024 |
| Speakeasy Coaching Ltd | Professional & scientific | 2008 |
| Specialist Disposals Limited | Water & waste | 2015 |
| Spice India (Blandford Forum) Ltd | Hospitality | 2025 |
| Spiller Building & Roofing Ltd | Construction | 2015 |
| Sports Officials Consultancy Ltd | Arts & recreation | 2013 |
| Sprk Limited | Information & communication | 2025 |
| ST. Ann's Hill Management Company Limited | Households | 1987 |
| Stage Filler Ltd | Information & communication | 2024 |
| Stagecore Productions Limited | Arts & recreation | 2016 |
| Stanley Pond Limited | Real estate | 1955 |
| Stead Technology Ltd | Information & communication | 2016 |
| Stemark Logistics Ltd | Transport & logistics | 2020 |
| Stephen Crane Ltd | Construction | 2003 |
| Stephen J. Whitham Associates Limited | Professional & scientific | 2006 |
| Steve Quick Interior Solutions Limited | Other services | 2015 |
| Stickland Hill Farm Limited | Agriculture & fishing | 2012 |
| Stone Services Ltd | Professional & scientific | 2022 |
| Store IT Weymouth Limited | Transport & logistics | 2024 |
| Stour Contracts Ltd | Manufacturing | 2025 |
| Stour Therapy Ltd | Other services | 2022 |
| Stour Valley Civils Ltd | Professional & scientific | 2025 |
| Stour Valley Dog Rescue CIC | Education | 2025 |
| Strategiclogix Ltd | Professional & scientific | 2024 |
| Stray Dog Bars Ltd | Wholesale & retail | 2022 |
| Stride Commerce Ltd | Wholesale & retail | 2023 |
| Studio Eight Films Ltd | Information & communication | 2025 |
| Suflex Limited | Wholesale & retail | 1933 |
| Summerwood Homes Limited | Real estate | 1988 |
| Sunbeams Day Care Limited | Health & social care | 2007 |
| Sunflowerraes Ltd | Wholesale & retail | 2026 |
| Supercharge Your Dreams Ltd | Professional & scientific | 2026 |
| Supply Sustainable Solutions UK Ltd | Manufacturing | 2018 |
| Sustainable Media Ltd | Professional & scientific | 2026 |
| Swann PUB Management Ltd | Hospitality | 2024 |
| Sweetland Property Solutions Ltd | Other services | 2018 |
| Sweetwater Music Ltd | Arts & recreation | 2016 |
| Swift Agri Limited | Administrative & support | 2009 |
| Swim Teachers Network Limited | Administrative & support | 2020 |
| Sycos (U.K.) Limited | Professional & scientific | 1983 |
| Synallagma Ltd | Professional & scientific | 2017 |
| T Properties & Lettings Ltd | Real estate | 2025 |
| T T Motors Racing Limited | Wholesale & retail | 2001 |
| T.C.M. & Health UK Ltd | Health & social care | 2012 |
| Tactical Edge Training Ltd | Education | 2025 |
| Tarhinton Farms Limited | Agriculture & fishing | 1960 |
| Tarrant Keyneston Management Company Limited | Households | 2000 |
| Tasuma (UK) Limited | Manufacturing | 1984 |
| Teddy Rocks Festival Limited | Arts & recreation | 2021 |
| TEDDY20 Supporting Children With Cancer Limited | Health & social care | 2016 |
| Tedsss Ltd | Professional & scientific | 2012 |
| Telesoft Technologies Limited | Information & communication | 1989 |
| Tenleft Ltd | Information & communication | 2024 |