| Steve Jones Holdings Limited | Construction | 1998 |
| Sticks and Bones Ltd | Hospitality | 2024 |
| Sticky Green Investments Limited | Construction | 2022 |
| Stile Lane Management Company Limited | Households | 1994 |
| Stinsford Holdings Ltd | Financial services | 2023 |
| Stinsford House Management Company Limited | Real estate | 1999 |
| Stitchinghouse Design Limited | Wholesale & retail | 2003 |
| Stoborough Meadow Management Company Limited | Households | 1997 |
| Stockley Builders Limited | Construction | 2009 |
| Stone Marine Limited | Manufacturing | 1946 |
| Stone Marine Propulsion Limited | Manufacturing | 1917 |
| Stone Marine Shipcare Limited | Manufacturing | 1898 |
| Stonecoast Creative Ltd | Professional & scientific | 2015 |
| Stonecraft Homes Ltd | Construction | 2023 |
| Stonehaven 5 Studland Road Ltd | Construction | 2025 |
| Stonehill Court Limited | Households | 1995 |
| Stonetec Distribution UK Limited | Wholesale & retail | 2015 |
| Store-It Dorchester Ltd | Professional & scientific | 2018 |
| Storm in a Teacup Productions Ltd. | Information & communication | 2012 |
| Strata Edge Enterprises Ltd | Wholesale & retail | 2025 |
| Strathmore House (Poundbury) Management Company Limited | Households | 2015 |
| Stress Recordings Limited | Information & communication | 1990 |
| Strong IRL Ltd | Wholesale & retail | 2024 |
| Strout & Sons Ltd | Agriculture & fishing | 2026 |
| Studio Cetra Ltd | Information & communication | 2025 |
| Studio Jagger & Mckenzie LLP | | 2015 |
| Studio Kootos Ltd | Professional & scientific | 2017 |
| Studio Wake Ltd | Professional & scientific | 2026 |
| Studley's Motorcycles Ltd | Wholesale & retail | 2010 |
| Stunt Consulting Limited | Professional & scientific | 2020 |
| Stunt Equestrian Limited | Agriculture & fishing | 2018 |
| Submarine Atmosphere Control Equipment Limited | Other services | 2022 |
| Subpar BUT Ltd | Information & communication | 2021 |
| Sultan Peptides Ltd | Professional & scientific | 2025 |
| Summerfield Property Improvements Ltd | Construction | 2019 |
| Summerhill Care (Dorset) Limited | Health & social care | 2024 |
| Summit Digital Consulting Ltd | Information & communication | 2024 |
| Sundial Landscapes (Dorset) Ltd | Administrative & support | 2014 |
| Sunken Trampolines Limited | Administrative & support | 2013 |
| Sunny Day Nurseries Limited | Education | 2001 |
| Sunny Days Bridport Limited | Education | 2015 |
| Sunny Days Dorchester Limited | Education | 2015 |
| Sunshineradio Media Group Limited | Information & communication | 2024 |
| Suntara Limited | Health & social care | 2019 |
| Superbike Parts Ltd | Wholesale & retail | 2024 |
| Supreme PH7 Ltd | Construction | 2017 |
| Surehoardstag Fencing (CC) Ltd | Construction | 2017 |
| Surehoardstag Fencing (DC) Ltd | Construction | 2017 |
| Surenough Limited | Agriculture & fishing | 1983 |
| SURFACE2AIR Developments Ltd | Construction | 2024 |
| Surgery Maintenance Services Ltd | Health & social care | 2014 |
| Sustudio Limited | Arts & recreation | 2022 |
| SW Estates Limited | Construction | 2003 |
| SWC Autos Ltd | Wholesale & retail | 2018 |
| Sweet Potato Publishing Ltd | Information & communication | 2020 |
| Sydling Biomass Limited | Energy | 2012 |
| Sydling Brook Investment Company Limited | Financial services | 2019 |
| Sydling Springs Management Company Limited | Households | 1991 |
| Sylv & V Limited | Hospitality | 2019 |
| Symonds & Sampson LLP | | 2007 |
| Synergy Home Solutions Ltd | Construction | 2023 |
| Synergy Plus LLP | | 2010 |
| Syntagma Holdings Limited | Financial services | 2020 |
| T Bamlet Limited | Agriculture & fishing | 1960 |
| T H Richards Limited | Construction | 2025 |
| T Hook Enterprises Limited | Wholesale & retail | 2021 |
| T J Sports Associates Ltd | Professional & scientific | 2017 |
| T&R Recycling Ltd | Wholesale & retail | 2021 |
| T.J.M. Travel Limited | Administrative & support | 1991 |
| Tackle Finance Limited | Financial services | 2003 |
| Tailor Made London Ltd | Wholesale & retail | 2008 |
| Tailor Made Shoreditch Limited | Financial services | 2017 |
| Taiti Aerospace Ltd | Professional & scientific | 2014 |
| Talisco Limited | Real estate | 1986 |
| Tall House Digital Limited | Information & communication | 2010 |
| Tallula Property Limited | Households | 2022 |
| Tamander Limited | Information & communication | 1998 |
| Tamarisk Farm Limited | Agriculture & fishing | 2003 |
| Tandem Architects Limited | Professional & scientific | 2016 |
| Tandoori Spice Restaurant Ltd | Hospitality | 2019 |
| Tanya Green Counselling and Psychotherapy Ltd | Health & social care | 2023 |
| Tapamara Limited | Hospitality | 2015 |
| Tappenden (Wickham) Limited | Other services | 1993 |
| Tarasell Limited | Hospitality | 1995 |
| Tarousel Media Management Limited | Arts & recreation | 2014 |
| Tatlong Daan Ltd | Transport & logistics | 2023 |
| Tattie Rose Flowers Limited | Other services | 2012 |
| Taurean Estates Ltd | Administrative & support | 2026 |
| Taylor Isgar Commercial Limited | Real estate | 2022 |
| Taylor Isgar Ltd | Real estate | 2023 |
| TC Management Dorchester Limited | Construction | 2015 |
| Tcgbay Ltd | Wholesale & retail | 2025 |
| Tea Cabin (Weymouth) Limited | Hospitality | 2004 |
| Tea on the Green (Dorset) Limited | Hospitality | 2016 |
| Teach Perfect Limited | Education | 2017 |
| Team JEL Limited | Professional & scientific | 2012 |
| TEC Services & Autocare Ltd | Wholesale & retail | 2021 |
| Tech NET Solutions Ltd | Wholesale & retail | 2024 |
| Techaxis Engineering Limited | Arts & recreation | 1978 |
| Technological Limited | Information & communication | 2019 |