| SGC Homes Limited | Real estate | 2024 |
| Shamrock Finescale Ltd | Manufacturing | 2021 |
| Shamrock Media Productions Ltd | Arts & recreation | 2016 |
| Shamrock Trains Ltd | Manufacturing | 2010 |
| Sharan Haine Ltd | Information & communication | 2025 |
| Shared Horizons Ltd | Health & social care | 2025 |
| Shell Bay Property Ltd | Real estate | 2022 |
| Sheridan Consulting South Ltd | Professional & scientific | 2023 |
| Shoreline Heating Ltd | Construction | 2002 |
| Shoreside Swanage Limited | Wholesale & retail | 2019 |
| Sigma Accountancy Services Limited | Professional & scientific | 2015 |
| Silverlake Therapies Ltd | Health & social care | 2020 |
| Simon Burrow Productions LLP | | 2017 |
| SJ UK Consulting Ltd | Information & communication | 2024 |
| Skybridge Lending Limited | Financial services | 2017 |
| Skytronix Ltd | Education | 2023 |
| SLC Group Ltd | Hospitality | 2019 |
| SLP Management Solutions Ltd | Professional & scientific | 2019 |
| Smart Travel Group Ltd | Administrative & support | 2024 |
| Smarter Complaints Ltd. | Information & communication | 2012 |
| Smashing Windows (in Swanage) Ltd | Other services | 2002 |
| Smiths Vintage Ltd | Wholesale & retail | 2006 |
| Smoke on the Water Limited | Hospitality | 2023 |
| Social Independence Support Services Ltd | Health & social care | 2016 |
| Sold to YOU Limited | Manufacturing | 2023 |
| Soundar Ltd | Information & communication | 2025 |
| South Coast Karting Limited | Arts & recreation | 2004 |
| South Coast Sail and Power Ltd | Transport & logistics | 2020 |
| South Dorset Coaches Limited | Transport & logistics | 2006 |
| South Side Publishing Limited | Information & communication | 1983 |
| Southam Contracting Services Ltd | Construction | 2014 |
| Southcore Properties Limited | Households | 1985 |
| Southern Counties Engineering Services Limited | Other services | 1995 |
| Southside Construction Ltd | Construction | 2025 |
| Spanner Films Limited | Information & communication | 2002 |
| Sparkle Cleaning Services (Swanage) Ltd | Other services | 2007 |
| Sparkling Windows and Carpets TOO Limited | Administrative & support | 2002 |
| Spencer Mews Management Company Limited | Households | 2017 |
| Spizy POT Limited | Hospitality | 2026 |
| Springhill House Freehold Limited | Households | 2001 |
| Spyway Mews Management Company Ltd | Households | 2022 |
| SRA Agency & Productions Ltd | Arts & recreation | 2001 |
| Ssas Manager Ltd | Administrative & support | 2025 |
| SSB Maintenance Dorset Ltd | Construction | 2024 |
| ST Marks Mews Management Company Limited | Households | 2017 |
| ST Michaels Garage Limited | Wholesale & retail | 2014 |
| ST. Michaels Guesthouse (Swanage) Limited | Hospitality | 2002 |
| Stafford Court Flats (Swanage) Limited | Households | 2020 |
| Stafford House (Swanage) Management Limited | Households | 1998 |
| Stafford Mews Freehold Management Company Limited | Households | 2020 |
| Stage Light Sound Events Ltd | Information & communication | 2019 |
| Stage Light Sound Ltd | Information & communication | 2015 |
| Stainers Limited | Real estate | 2026 |
| Station Mews (Wareham) Management Co Limited | Households | 2014 |
| Steeden Carpentry Limited | Construction | 2003 |
| Steepways Management Co. Limited | Households | 1984 |
| Step Into Sport Limited | Education | 2025 |
| Stephen Hurford Management Limited | Administrative & support | 2012 |
| Stingray Sports Boat UK Ltd | Wholesale & retail | 2010 |
| Stokesi Ltd | Manufacturing | 2023 |
| Storer (Coventry) Limited | Real estate | 1941 |
| Strange Productions Limited | Professional & scientific | 2009 |
| Strike Scaffolding Ltd | Construction | 2012 |
| Stripped Unzipped Limited | Arts & recreation | 2021 |
| STS Lettings Ltd | Real estate | 2014 |
| Studland Stores Limited | Wholesale & retail | 2018 |
| Sub-Surface Specialist Limited | Professional & scientific | 2017 |
| SUE Banner Limited | Administrative & support | 2013 |
| Sue's Cards Ltd | Wholesale & retail | 2023 |
| Summit Developments South Limited | Construction | 2014 |
| Suncliffe Court Swanage Limited | Real estate | 2004 |
| Sunnydale Gardens Ltd | Households | 2019 |
| Sunridge Close Limited | Other services | 2010 |
| Surface SOS Ltd | Construction | 2021 |
| Surfari Limited | Wholesale & retail | 2001 |
| Surprise "N" Store Limited | Wholesale & retail | 1999 |
| Susan Roberts Academy of Performing Arts Ltd | Arts & recreation | 1996 |
| Susten Energy Tech Investments GP Ltd | Financial services | 2025 |
| Susten Limited | Financial services | 2021 |
| Susten Nominees Limited | Professional & scientific | 2019 |
| Suttle & Co Ltd | Professional & scientific | 2023 |
| Swan INK Ltd | Other services | 2022 |
| Swanage and District Angling Club Limited | Arts & recreation | 2018 |
| Swanage and Dorset Scaffolding and Roofing Ltd | Construction | 2010 |
| Swanage and Purbeck Development Trust | Health & social care | 2013 |
| Swanage and Purbeck Group Limited | Wholesale & retail | 2018 |
| Swanage Angling Centre Ltd | Wholesale & retail | 2010 |
| Swanage Apparel Ltd | Manufacturing | 2025 |
| Swanage Associated Taxis Ltd | Transport & logistics | 2012 |
| Swanage Auto Centre Limited | Wholesale & retail | 2001 |
| Swanage Bay Holdings Ltd | Hospitality | 2024 |
| Swanage Beach Kiosk Ltd | Hospitality | 2019 |
| Swanage Boat Charters Ltd | Transport & logistics | 2009 |
| Swanage Bowling Club Limited | Arts & recreation | 2019 |
| Swanage Building Services Ltd | Construction | 2009 |
| Swanage Carnival (Marquee) Limited | Other services | 2000 |
| Swanage Cleaning Services Ltd | Administrative & support | 2021 |
| Swanage Cycling Club Ltd | Arts & recreation | 2019 |
| Swanage Dairy Limited | Wholesale & retail | 1999 |
| Swanage Dairy Properties Limited | Real estate | 2008 |