| Solar Eco UK Ltd | Construction | 2020 |
| Solas Banc Real Estate Ltd | Real estate | 2021 |
| Solas Realta Ltd | Professional & scientific | 2016 |
| Solent Auto Spares (Exports) Limited | Real estate | 1973 |
| Solent Construction (Hampshire) Limited | Construction | 2018 |
| Solent Effluent Systems Limited | Administrative & support | 2016 |
| Solent Marine Services & Sales Limited | Manufacturing | 2016 |
| Solent Party Ship Cruises Ltd | Transport & logistics | 2003 |
| Solent Pharma Ltd | Professional & scientific | 2010 |
| Solent Student Residences Limited | Professional & scientific | 1971 |
| Solent Turf Supplies Limited | Administrative & support | 1987 |
| Solent Water Services Limited | Water & waste | 2002 |
| Soley Studios Limited | Information & communication | 2023 |
| Solo Engineering Solutions Limited | Manufacturing | 2018 |
| Solus FS Limited | Administrative & support | 2001 |
| Solution Placements Limited | Administrative & support | 2016 |
| Solutions Social Work Limited | Health & social care | 2018 |
| Somac House Limited | Real estate | 2017 |
| Somborne HR Limited | Administrative & support | 2019 |
| Somebody Limited | Administrative & support | 2020 |
| Something From Nothing Limited | Arts & recreation | 2018 |
| Sonar UK Limited | Information & communication | 2005 |
| Sonnets Theatre Arts School Limited | Education | 2011 |
| Soper Grove Management Company Limited | Households | 2012 |
| Sora Risk Solutions Limited | Information & communication | 2018 |
| Sorbell Ltd | Real estate | 2022 |
| Sound and Rigging Solutions Ltd | Arts & recreation | 2009 |
| Soundbite Productions Limited | Information & communication | 2010 |
| South Coast Compliance Ltd | Professional & scientific | 2021 |
| South Coast Fencing Ltd | Manufacturing | 2020 |
| South Coast Floors Ltd | Wholesale & retail | 2019 |
| South Downs Fencing Ltd | Administrative & support | 2021 |
| South Downs Secure Limited | Real estate | 2017 |
| South Downs Venison and Game Limited | Agriculture & fishing | 2008 |
| South East Motors Ltd | Wholesale & retail | 2021 |
| South Lynch Estate Limited | Agriculture & fishing | 1988 |
| South Lynch Products Limited | Professional & scientific | 2024 |
| South Star AI Ltd | Information & communication | 2024 |
| South Wonston Nursery School Limited | Education | 1979 |
| Southampton Cruise Parking Limited | Transport & logistics | 2019 |
| Southampton Design and Print Limited | Manufacturing | 2002 |
| Southampton House Management Ltd | Households | 2014 |
| Southdown Shawford Management Limited | Households | 1982 |
| Southern ENT Limited | Health & social care | 2015 |
| Southern Executive Travel Limited | Transport & logistics | 2008 |
| Southern GAS Experts Limited | Manufacturing | 2013 |
| Southern Granary Services Limited | Agriculture & fishing | 2003 |
| Southern GT Limited | Extraterritorial | 2004 |
| Southern GT40 Ltd | Manufacturing | 2023 |
| Southern Investments Limited | Real estate | 2015 |
| Southern Planning Practice Ltd | Professional & scientific | 1999 |
| Southern Sheet Metal Limited | Manufacturing | 1986 |
| Southgate Gardens Management Ltd | Households | 2018 |
| Southgate Property Estates Limited | Real estate | 2025 |
| Southview Medical Ltd | Health & social care | 2025 |
| Southwest Dental Limited | Health & social care | 2013 |
| Southwick Group Limited | Professional & scientific | 2019 |
| Sovereign Bathrooms Winchester Ltd | Other services | 2017 |
| SP Funding Limited | Real estate | 2015 |
| Spade's Landscapes Ltd | Administrative & support | 2019 |
| Sparge Limited | Manufacturing | 2016 |
| Spark & Wire Limited | Construction | 2020 |
| Spark IT Systems Ltd | Information & communication | 2025 |
| Sparkford Chemicals Limited | Wholesale & retail | 1966 |
| Sparking Curiosity Limited | Wholesale & retail | 2017 |
| Sparkle Clean Professional Limited | Administrative & support | 2019 |
| Sparkvision AI Ltd | Information & communication | 2025 |
| Sparrowgrove and Oakwood Copse Conservation Trust | Other services | 2008 |
| Sparsholt College Services Limited | Administrative & support | 2018 |
| Sparsholt Developments Limited | Construction | 2017 |
| Sparsholt Wines Limited | Agriculture & fishing | 2022 |
| Sparx Beauty Limited | Other services | 2012 |
| Spash Estates Ltd | Real estate | 2026 |
| Speaker Bespoke Ltd | Professional & scientific | 2024 |
| Spearfish Security Ltd | Administrative & support | 2009 |
| Spearpoint Estates Limited | Real estate | 2025 |
| Special Advertising Services Ltd | Professional & scientific | 2023 |
| Spectre Worldwide Limited | Information & communication | 2017 |
| Spectrum Interactive (UK) Limited | Information & communication | 1998 |
| Spectrum Interactive Limited | Professional & scientific | 2002 |
| Speed 1971 Limited | Transport & logistics | 1991 |
| Spencechologies Ltd | Education | 2022 |
| Spero Vision Ltd | Wholesale & retail | 2026 |
| Spicesanjh Ltd | Real estate | 2020 |
| Spicymart Ltd | Hospitality | 2019 |
| Spinnaker Nominees Limited | Financial services | 2013 |
| Spiral Events Ltd | Administrative & support | 2019 |
| Spire Medical Limited | Extraterritorial | 2023 |
| Spiring Ltd | Other services | 2018 |
| Spiro Fire & Security Ltd | Public administration | 2026 |
| Spirota Ltd | Professional & scientific | 2022 |
| Splat Studio Limited | Arts & recreation | 2026 |
| Spoolup Ltd | Wholesale & retail | 2025 |
| Sportarium Trucks Limited | Arts & recreation | 2026 |
| Spotless Home (Winchester) Limited | Administrative & support | 2009 |
| Spotlight Advertising Ltd | Professional & scientific | 2024 |
| Spotlight Education UK Limited | Education | 2010 |
| Spotme Ltd | Information & communication | 2025 |
| Spratley Property Ltd | Real estate | 2025 |
| Spring Pond Farming Limited | Agriculture & fishing | 1996 |