| Sawers Properties Limited | Real estate | 2024 |
| Sayhirealtor.Com Ltd | Professional & scientific | 2022 |
| SB Tech Electrical Ltd | Construction | 2016 |
| SBA Housing Limited | Real estate | 2017 |
| SC Harbour Limited | Professional & scientific | 2014 |
| SC Homes & Houses Ltd | Real estate | 2024 |
| SC Landscaping Ltd | Administrative & support | 2015 |
| Scaffold Access Structures Limited | Construction | 2003 |
| Scamp Limited | Construction | 1997 |
| Scandor Landscapes Limited | Administrative & support | 2017 |
| Scandor Limited | Administrative & support | 2016 |
| Scarle Property Co. Limited | Real estate | 1954 |
| Scarlet Water Ltd | Water & waste | 2023 |
| Scene the Light Ltd | Information & communication | 2007 |
| Scenery Solutions Trading Ltd | Arts & recreation | 2014 |
| Schand Ltd | Administrative & support | 2014 |
| Schillingtons Limited | Professional & scientific | 2014 |
| Scholars' Walk (Desborough Road) Management Company Limited | Households | 2018 |
| SCI (Contracting) Limited | Construction | 2024 |
| Scientist Practitioner Limited | Health & social care | 2008 |
| SCJ Group Limited | Construction | 2021 |
| Scope Brickwork Ltd | Construction | 2015 |
| Scott - Drummond Limited | Manufacturing | 1977 |
| Scott Holdings Limited | Real estate | 2022 |
| Scott O'Shea - Health and Performance Coaching Ltd | Other services | 2015 |
| Scottow Services Limited | Construction | 2006 |
| Scroll Engineering Limited | Manufacturing | 2001 |
| Scylla Solutions Limited | Administrative & support | 2018 |
| Scythe Systems Ltd | Administrative & support | 2026 |
| SDR Accounting & Business Solutions Ltd | Professional & scientific | 2017 |
| Sdrd Property Ltd | Real estate | 2025 |
| Sea Bright Education Limited | Education | 2025 |
| Sea COT Limited | Hospitality | 2020 |
| Seacole Health Care Personnel Ltd | Extraterritorial | 2015 |
| Seagrass Bay Ltd | Wholesale & retail | 2022 |
| Search-South.Com Limited | Information & communication | 2004 |
| Seasonal Comforts Limited | Extraterritorial | 2022 |
| Seawork Marine Services Limited | Administrative & support | 1993 |
| Secretstartups Ltd | Education | 2025 |
| Section 23 Ltd | Administrative & support | 2021 |
| Sectona Technologies UK Private Limited | Information & communication | 2024 |
| Secure Garage Doors Limited | Extraterritorial | 2010 |
| Secure IP Solutions Ltd | Information & communication | 2016 |
| Secure Meters (UK) Limited | Administrative & support | 1987 |
| Secure Meters Assets Operator Limited | Financial services | 2012 |
| Secure Smso Limited | Information & communication | 2017 |
| Securehome Commercial Limited | Real estate | 2013 |
| Securehome Holdings Limited | Real estate | 1991 |
| Securehome Land Limited | Real estate | 2018 |
| Securehome Residential Limited | Real estate | 2008 |
| Secureshare Property Management Limited | Households | 1989 |
| Segensworth Management Company Limited | Real estate | 1988 |
| SEL (Yachts) LLP | | 2024 |
| Select Conveyancers Limited | Professional & scientific | 1996 |
| Selesa Limited | Construction | 2004 |
| Selwood Group Limited | Construction | 1994 |
| Selwood Holdings Limited | Financial services | 2007 |
| Selwood Ltd | Construction | 1951 |
| SEM Booster Limited | Professional & scientific | 2013 |
| Sentry Alert Systems Ltd | Administrative & support | 2019 |
| Sequin Limited | Professional & scientific | 2004 |
| Serendipitas Limited | Other services | 2017 |
| Services Direct Internet Limited | Information & communication | 2012 |
| Settle-Up Limited | Extraterritorial | 2023 |
| Seward (Dorset) Limited | Transport & logistics | 2002 |
| SF Creative Design Limited | Real estate | 2012 |
| SFK Consulting Engineers Limited | Professional & scientific | 2025 |
| SFK Consulting Limited Liability Partnership | | 2002 |
| SFK Consulting Network Ltd | Professional & scientific | 2012 |
| SFK Consulting Trustees Limited | Other services | 2026 |
| SFT (Southampton) Management Limited | Hospitality | 2000 |
| SFT Property Ltd | Real estate | 2021 |
| SG Nutrition Ltd | Health & social care | 2016 |
| SGA Consultants Limited | Professional & scientific | 2007 |
| Sgent Property Ltd | Real estate | 2023 |
| Sgrd Saran Ltd | Financial services | 2024 |
| Sh@Rd Business and Consulting Services Limited | Professional & scientific | 2023 |
| Shading Places Limited | Wholesale & retail | 2012 |
| Shake Testing and Consultancy Limited | Professional & scientific | 2025 |
| Shakers Bar and Catering Supplies Limited | Wholesale & retail | 2014 |
| Shallow Consultancy Company Ltd | Information & communication | 2021 |
| Shallwedanceuk Ltd | Education | 2025 |
| Sharemoney Europe Limited | Administrative & support | 2010 |
| Sharing Space Ltd | Health & social care | 2025 |
| Shatteredpanda Ltd | Professional & scientific | 2012 |
| Shaw's Estates Limited | Real estate | 2024 |
| SHB Investments Limited | Professional & scientific | 2020 |
| SHB Logistics Limited | Professional & scientific | 2018 |
| Shelley Computech Ltd | Information & communication | 2018 |
| Shelving Solutions Limited | Construction | 2010 |
| SHEPP999-MEDICAL Ltd | Health & social care | 2016 |
| Sheprail Ltd | Construction | 2020 |
| Sherfield Design Limited | Professional & scientific | 2007 |
| Sherlock and Watson Ltd | Wholesale & retail | 2007 |
| Shgp Limited | Health & social care | 2017 |
| Shillingstone LLP | | 2015 |
| Shining Light Consultancy Limited | Information & communication | 2002 |
| Shining Light Property Investments Limited | Real estate | 2002 |
| Shirley Preschool Limited | Health & social care | 2021 |
| Shiv Shetti Limited | Professional & scientific | 2018 |