| Safeguard Fire Equipment | | 1994 |
| Safeguard Fire Equipment | | 2002 |
| Sahara (Melksham) Limited | Water & waste | 1947 |
| Salisbury Cathedral School Limited | Education | 2002 |
| Salisbury Cathedral Works Department Limited | Construction | 1994 |
| Salisbury Museum Replicas Limited | Wholesale & retail | 1969 |
| Salisbury Printing Company Limited | Manufacturing | 1982 |
| Samuel & Sons Property Management LLP | | 2023 |
| Samurai Limited | Hospitality | 2018 |
| Sandy Ridge Property Management Company Limited | Households | 1998 |
| Sarasola Limited | Information & communication | 2006 |
| Sarum College Services Limited | Hospitality | 1985 |
| Savencia Fromage & Dairy UK Ltd | Wholesale & retail | 1958 |
| Savernake Property Consultants Limited | Professional & scientific | 2005 |
| Sdcivilconsultant Ltd | Construction | 2023 |
| Sebring Consulting Limited | Information & communication | 2007 |
| Secure Wireless Solutions Ltd | Information & communication | 2004 |
| Shades Window Films Ltd | Construction | 2007 |
| Shah & Company Limited | Administrative & support | 1996 |
| Shing MUN Limited | Other services | 2001 |
| Shining Minds Limited | Administrative & support | 2005 |
| Shm-Tech Limited | Extraterritorial | 2016 |
| Shoe Garage Limited | Wholesale & retail | 1989 |
| Short Systems Limited | Information & communication | 1993 |
| Shrivenham Park Golf Club Limited | Arts & recreation | 2007 |
| Shruti Ltd | Wholesale & retail | 1990 |
| Sian Waste Management Ltd | Hospitality | 2021 |
| Sidecliffe Ltd | Administrative & support | 1995 |
| Silverlace Limited | Information & communication | 2004 |
| Simon Colligan Estate Agents Ltd | Real estate | 2003 |
| Simon Day Limited | Professional & scientific | 2002 |
| Sirojel MD Ltd | Construction | 2016 |
| SJP Studios Ltd | Professional & scientific | 2013 |
| Skimming Stones Limited | Information & communication | 2003 |
| Slades of Devizes Limited | Wholesale & retail | 2000 |
| Sleepmaker Beds Limited | Professional & scientific | 1943 |
| SM Automation Ltd | Information & communication | 2007 |
| Snap Electrical Limited | Construction | 2001 |
| Software Syntax Limited | Other services | 1986 |
| Solutions Property Finder Services Limited | Professional & scientific | 2007 |
| Somerford Holdings Limited | Professional & scientific | 2003 |
| Sopwith Park Holdings Limited | Arts & recreation | 1988 |
| Sorbtec Limited | | 1982 |
| Sorvio Insurance Brokers Limited | Financial services | 1993 |
| Sound Knowledge Limited | Wholesale & retail | 2004 |
| Southern Independent Health Ltd | Health & social care | 2006 |
| SP Jones Ltd | Construction | 2015 |
| Spacefleet Ltd | Transport & logistics | 2004 |
| Spatial Data Engineering Limited | Information & communication | 1998 |
| Specialist Instruments Limited | Administrative & support | 2001 |
| Spire Solutions (UK) Limited | Professional & scientific | 2006 |
| Springfords and Rose Limited | Manufacturing | 1958 |
| Springmaster Limited | Professional & scientific | 1999 |
| Springvale Properties Limited | Construction | 1972 |
| Sprungfoam Limited | Professional & scientific | 1955 |
| Square Mile Systems Limited | Information & communication | 2004 |
| ST. Joseph's Nursery | Education | 2007 |
| ST. Mary's Street Practice Limited | Health & social care | 2006 |
| Stable Business Limited | Professional & scientific | 2003 |
| Stable Cottages Management Company Limited | Households | 2002 |
| Stanton Developments Limited | Wholesale & retail | 1989 |
| Star News Limited | Wholesale & retail | 2002 |
| Starmaid Limited | Extraterritorial | 2004 |
| Starwulf Limited | Wholesale & retail | 2007 |
| Station Garage (Swindon) Limited | | 1979 |
| Stereon Metals Calne Ltd | Manufacturing | 1993 |
| Steven Clements Fairs Limited | Administrative & support | 2007 |
| Stevenson Construction (SW) Ltd | Construction | 2021 |
| Stonehenge Cycles Limited | Wholesale & retail | 2003 |
| Stonewood Design Holdings Limited | Professional & scientific | 2021 |
| STRAIGHT8STUDIOS Limited | Professional & scientific | 2013 |
| Straightline Paving Limited | Construction | 2007 |
| Strategenic Limited | Professional & scientific | 2001 |
| SUE Mitchell Limited | Professional & scientific | 2003 |
| Summit Osteopathy Limited | Health & social care | 2002 |
| Sun Teck Ltd | Professional & scientific | 2015 |
| Sureway Contractors Limited | | 1987 |
| Surveying and Scientific Instruments Limited | Real estate | 1975 |
| Swanglen Furnishings Limited | Professional & scientific | 1971 |
| Swindon Asbestos Surveying Limited | Professional & scientific | 2006 |
| Swindon Black CAB Co Limited | Transport & logistics | 1999 |
| Switchview Developments Limited | Real estate | 1998 |
| System Twelve Limited | Real estate | 2003 |
| Systems at Work Limited | Information & communication | 1998 |
| Sytec - Systems and Technology Limited | Information & communication | 2000 |
| T and a Motors Limited | Wholesale & retail | 2001 |
| T C Design Consultants Limited | Professional & scientific | 2001 |
| T J Gillman Property Ltd | Real estate | 2022 |
| T. H. White Holdings Limited | Professional & scientific | 1914 |
| T. H. White Limited | Manufacturing | 1953 |
| T.H. White, Installation, Limited | Manufacturing | 1978 |
| T.W. Landscapes Limited | Administrative & support | 1995 |
| Tailfeather Studios Ltd | Arts & recreation | 2026 |
| Tamarin Investments Limited | Professional & scientific | 1995 |
| Tania Richardson Ltd | Professional & scientific | 2026 |
| Targeteasy Limited | Real estate | 2000 |
| TBF (UK) Limited | Wholesale & retail | 1998 |
| Terry Cain (Property Consultants) Limited | Real estate | 2003 |
| Teslar Consulting Limited | Professional & scientific | 2014 |
| TG Jones Promotions Limited | Wholesale & retail | 1989 |