| Sandymount Windows and Doors Ltd | Construction | 2015 |
| Sanford Court Management Company Limited | Households | 1988 |
| Sanghera Property Ltd | Households | 2023 |
| Sanitus Limited | Wholesale & retail | 2025 |
| Sanneson Accountancy Ltd | Professional & scientific | 2010 |
| Sanneson Contractors Limited | Construction | 2020 |
| Sanneson Staffing Limited | Administrative & support | 2021 |
| Sanneth Foods Ltd | Hospitality | 2011 |
| Sansum Evans Limited | Administrative & support | 2023 |
| Santi Swindon Ltd | Hospitality | 2024 |
| Santriya Properties Ltd | Real estate | 2025 |
| Sanwin Solutions Ltd | Manufacturing | 2026 |
| SAP Legal Services Limited | Professional & scientific | 2020 |
| SAR Business Services Ltd | Health & social care | 2019 |
| SAR Motors Ltd | Wholesale & retail | 2018 |
| SAR Property Services Ltd | Real estate | 2025 |
| Sarah Ellis Business Consultancy Limited | Professional & scientific | 2006 |
| Sarah Jane Kimber Limited | Health & social care | 2021 |
| Sarah Jones Consultancy Ltd | Professional & scientific | 2016 |
| Sarah Tkaczyk Ltd | Professional & scientific | 2025 |
| Saramm UK Ltd | Manufacturing | 2025 |
| Sarao Transport UK Ltd | Transport & logistics | 2023 |
| Sardaya Enterprises Ltd | Other services | 2013 |
| Sardo Electrical Ltd | Construction | 2025 |
| Sariska Online Ltd. | Wholesale & retail | 2010 |
| Sarj Investments Ltd | Real estate | 2024 |
| Sark Property Maintenance Limited | Administrative & support | 2010 |
| Sarsen & Wold Ltd | Wholesale & retail | 2025 |
| Saru 365 Ltd | Information & communication | 2021 |
| Saru Solutions Ltd | Information & communication | 2022 |
| Sarys Ltd | Construction | 2025 |
| SAS Elite Ltd | Construction | 2018 |
| SAS Rope & Rail Ltd | Administrative & support | 2004 |
| Sasa Building Products Ltd | Real estate | 2006 |
| Sashasov Assets Ltd | Financial services | 2025 |
| Sashasov Consulting Ltd | Information & communication | 2022 |
| Sashasov Ltd | Real estate | 2021 |
| Sason Ltd | Transport & logistics | 2020 |
| Satellite & Space Consulting Ltd | Construction | 2022 |
| Satisbuy Limited | Wholesale & retail | 2020 |
| Satse Ltd | Health & social care | 2023 |
| Satti Logistics Ltd | Transport & logistics | 2019 |
| Sattvico Ltd | Wholesale & retail | 2026 |
| Satvic Trading Limited | Wholesale & retail | 2024 |
| Satviga-S Swindon Ltd | Wholesale & retail | 2025 |
| Sauce & Sizzle Ltd | Hospitality | 2024 |
| Saunders Complete Waste Management Limited | Water & waste | 2005 |
| Savannah Harvest Ltd | Construction | 2017 |
| Savannahrise Care Limited | Health & social care | 2019 |
| Savatrans Ltd | Transport & logistics | 2022 |
| Save Energies Ltd | Energy | 2023 |
| Save on Tyres Limited | Wholesale & retail | 2006 |
| Savele Limited | Administrative & support | 2025 |
| Savernake Court Management Company Limited | Households | 2004 |
| Savernake Manor Management Company Limited | Households | 2014 |
| Savoir-Faire Properties Limited | Construction | 2010 |
| Savory and Slatter Ltd | Construction | 2011 |
| Sawali Records Ltd | Information & communication | 2026 |
| Sawc Limited | Construction | 2026 |
| Saxaflute Ltd | Arts & recreation | 2020 |
| Saxon Close Limited | Households | 1984 |
| Saxon Compliance Ltd | Manufacturing | 2021 |
| Saxon Design & Build Limited | Construction | 2002 |
| Saxon Meadows Cricklade Residents Limited | Real estate | 1982 |
| Saxonia Investments Limited | Real estate | 2012 |
| Sayho Limited | Other services | 2019 |
| Sazure Ltd | Professional & scientific | 2025 |
| SB Butler Limited | Arts & recreation | 2026 |
| SB Global Services Ltd | Information & communication | 2021 |
| SB Heating Limited | Construction | 2017 |
| SB Nexus Limited | Administrative & support | 2002 |
| SBA Haulage Ltd | Transport & logistics | 2025 |
| SBD Swindon Ltd | Wholesale & retail | 2024 |
| Sbmmshop Ltd | Extraterritorial | 2024 |
| SBP Management Limited | Real estate | 1985 |
| SBR Construction Ltd | Construction | 2025 |
| SC Parker Limited | Financial services | 2024 |
| Scanamp Ltd | Information & communication | 2025 |
| Scapolo Ltd | Wholesale & retail | 2023 |
| Scarab Performance Composites Ltd | Manufacturing | 2018 |
| Scarcity Spot Ltd | Wholesale & retail | 2025 |
| Scarlet Orange Limited | Information & communication | 2005 |
| Scarlett Mcgurk Plumbing Solutions Ltd | Construction | 2017 |
| Scarlette Ltd | Health & social care | 2022 |
| Scarrotts Firewood Limited | Wholesale & retail | 2025 |
| Scarrotts Funfairs Limited | Arts & recreation | 2025 |
| SCD Installations & Joinery Limited | Construction | 2025 |
| SCG People Limited | Households | 2025 |
| SCG Tuitions Limited | Education | 2024 |
| SCH (UK) Ltd. | Real estate | 2012 |
| Schaffner Limited | Wholesale & retail | 1984 |
| Schirmacher Consulting Limited | Professional & scientific | 2010 |
| School Farm Solar Park Limited | Energy | 2014 |
| School House Court (Highworth) Limited | Households | 1996 |
| School of Black Belts LLP | | 2017 |
| Scion Interactive Limited | Information & communication | 2013 |
| Scion International Limited | Wholesale & retail | 2000 |
| Scissor Art 1 Barber Shop Ltd | Other services | 2019 |
| SCK Pharma Services Limited | Professional & scientific | 2015 |
| SCM Project Management Ltd | Financial services | 2017 |