| Slades Bransgore Limited | Real estate | 2024 |
| Slades Homes Ltd | Real estate | 2008 |
| Slatemark Residents Association Limited | Households | 1983 |
| Slcv Limited | Information & communication | 2025 |
| Sleep & Bloom Ltd | Health & social care | 2026 |
| Slim Thick Athleisure Limited | Wholesale & retail | 2020 |
| SM Bathrooms & Kitchens Limited | Construction | 2016 |
| Smartlike Ltd | Hospitality | 2024 |
| Smartworks Group Holdings Ltd | Financial services | 2025 |
| Smartworks Group Ltd | Construction | 2018 |
| Smartypac Ltd | Transport & logistics | 2016 |
| Smchiro Limited | Health & social care | 2019 |
| Smexpand Ltd | Information & communication | 2009 |
| SMJ Associates Limited | Information & communication | 2015 |
| Smoke & Flames Ltd | Hospitality | 2021 |
| SMP Brickwork Limited | Construction | 2008 |
| Smrt Sourcing Ltd | Administrative & support | 2023 |
| Smugglers Christchurch Limited | Hospitality | 2025 |
| Smugglers Reach Management Company Limited | Administrative & support | 1986 |
| Snadbanks Ltd | Professional & scientific | 2022 |
| Snell Heating & Renewables Ltd | Construction | 2024 |
| Snowtrax Limited | Arts & recreation | 1997 |
| Snowtrax Surfaces Limited | Construction | 2018 |
| SNS 79 Investments Limited | Professional & scientific | 2017 |
| SO Mote IT BE Ltd | Manufacturing | 2025 |
| Soapbox Spirits Ltd | Manufacturing | 2015 |
| Sofistra Limited | Professional & scientific | 1997 |
| Soft Life Studios Ltd | Manufacturing | 2025 |
| Soho Group Ltd | Hospitality | 2022 |
| Soho PUB Group Limited | Hospitality | 2025 |
| Solar Roda Limited | Wholesale & retail | 2022 |
| Solario Builders Ltd | Construction | 2006 |
| Solaris Property Development Ltd | Real estate | 2024 |
| Solarpowerlink Limited | Construction | 2010 |
| Solent Business Services Limited | Manufacturing | 2008 |
| Solent Electronics Limited | Professional & scientific | 2019 |
| Solent Steel Structures Limited | Construction | 2018 |
| Solios Energy Limited | Construction | 2023 |
| Solios Limited | Construction | 2023 |
| Sollywood Ltd | Professional & scientific | 2024 |
| Solutech Services Limited | Information & communication | 1996 |
| Solutionpath Limited | Information & communication | 2012 |
| Sopley Farm Buildings Limited | Real estate | 2012 |
| Sopley Garage Limited | Manufacturing | 2025 |
| Sort Stuff OUT Ltd | Wholesale & retail | 2019 |
| South Catering Equipment Limited | Wholesale & retail | 2013 |
| South Catering Fabrication Limited | Manufacturing | 2013 |
| South Coast Aesthetic Clinic Limited | Extraterritorial | 2016 |
| South Coast Cladding Ltd | Construction | 2016 |
| South Coast Decorating and Maintenance Ltd | Construction | 2022 |
| South Coast Electrical Ltd | Construction | 2024 |
| South Coast Fire Doors Ltd | Construction | 2019 |
| South Coast Fire Protection Ltd | Construction | 2014 |
| South Coast Golf Hub Ltd | Wholesale & retail | 2023 |
| South Coast Hosts (Residential) Limited | Real estate | 2020 |
| South Coast Hosts Ltd | Real estate | 2020 |
| South Coast Marine Boat and Chandlery Ltd | Wholesale & retail | 2019 |
| South Coast Media Ltd | Information & communication | 2012 |
| South Coast Properties Limited | Construction | 2003 |
| South Wessex Auto Sales Ltd | Wholesale & retail | 2024 |
| South West European Initiatives Limited | Administrative & support | 1998 |
| Southampton Harbour Hotel Ltd | Hospitality | 2011 |
| Southampton Kawasaki Ltd | Wholesale & retail | 2020 |
| Southampton Pest Control Ltd | Administrative & support | 2024 |
| Southern Contracts (Shipping) Limited | Other services | 1965 |
| Southern Domestic Appliances Ltd | Wholesale & retail | 2010 |
| Southern Fisheries Ltd | Administrative & support | 2005 |
| Southern Measured Surveys Ltd | Professional & scientific | 2024 |
| Southern Zinc Solutions Ltd | Construction | 2022 |
| Southwick Road Limited | Households | 2020 |
| Southwood Construction Limited | Construction | 2018 |
| Southwood Court RTM Company Limited | Households | 2006 |
| Sovereign Promotions Ltd | Professional & scientific | 2024 |
| Spadeco Ltd | Information & communication | 2015 |
| Spark Automated Services Ltd | Hospitality | 2025 |
| Sparta Recruitment Ltd | Administrative & support | 2021 |
| SPC Pest Control Ltd | Administrative & support | 2025 |
| Specialist Policing Consultancy Ltd | Professional & scientific | 2011 |
| Speciality Welds Limited | Manufacturing | 2004 |
| SPECUL8 Investments Limited | Real estate | 2018 |
| Spencer Cursley Group Limited | Hospitality | 2024 |
| Spherea Ltd | Professional & scientific | 2001 |
| Spherea Technology Ltd | Manufacturing | 2003 |
| Spherea Test & Services Ltd | Manufacturing | 2001 |
| Spira Technologies Limited | Information & communication | 2015 |
| Spires Consultancy Services Ltd | Professional & scientific | 2019 |
| Spirit Hairdressing Limited | Other services | 2003 |
| Spiritual Bollocks Limited | Wholesale & retail | 2022 |
| SPL Property Solutions Ltd | Real estate | 2020 |
| SPL Soft Furnishing Solutions Ltd | Manufacturing | 2024 |
| Splintgrade Limited | Financial services | 1976 |
| Springboard HR Ltd | Administrative & support | 2024 |
| SPS Building and Maintenance Contractors Limited | Construction | 2019 |
| Spurlings Christchurch LLP | | 2016 |
| Spyrosoft Ltd | Information & communication | 2016 |
| Squeaky Clean Bournemouth Ltd | Administrative & support | 2022 |
| Squires Group Limited | Administrative & support | 2020 |
| Ssjr Co 11 Limited | Construction | 2020 |
| Ssjr Co 12 Limited | Construction | 2021 |
| Ssjr Co 15 Limited | Construction | 2021 |