| Spacer Connect Limited | Extraterritorial | 2013 |
| SPC Estates Ltd | Administrative & support | 2018 |
| Specialist Cars of Southsea Limited | Wholesale & retail | 2016 |
| Specialist Endodontic Centre Limited | Health & social care | 2009 |
| Spencer Design & Build Limited | Construction | 2025 |
| Sphelele Limited | Health & social care | 2011 |
| Spice Island Chilli Ltd | Hospitality | 2017 |
| Spice Island House RTM Company Limited | Real estate | 2023 |
| Spice N Grill Limited | Hospitality | 2024 |
| Spice Property Ltd | Real estate | 2026 |
| SPICEHUB101 Ltd | Hospitality | 2025 |
| Spinnaker Windows & Conservatories Limited | Construction | 2008 |
| Sponsor Scientific Ltd | Professional & scientific | 2020 |
| Sporting Difference Limited | Administrative & support | 2013 |
| Spring ME to Limited | Information & communication | 2020 |
| Springboard Valuations Limited | Professional & scientific | 2021 |
| SPRK42 Ltd | Information & communication | 2025 |
| Square Accounts Limited | Professional & scientific | 2019 |
| Square 8 Ltd | Wholesale & retail | 2020 |
| Square Accounting Limited | Extraterritorial | 2025 |
| Square Agents Ltd | Professional & scientific | 2025 |
| Square PEG Architects Ltd | Professional & scientific | 2021 |
| SR Grill and Herbs Ltd | Hospitality | 2024 |
| SR Scaffolding (South) Ltd | Construction | 2020 |
| SRC Assessments Limited | Health & social care | 2014 |
| Sridhar Ramasamy Limited | Wholesale & retail | 2019 |
| SRL Investments Holdings Limited | Financial services | 2025 |
| SS FL Ltd | Wholesale & retail | 2024 |
| Ssbd Nails Ltd | Other services | 2009 |
| ST Andrews Road Management Company Limited | Professional & scientific | 2000 |
| ST Francis Garage Ltd | Wholesale & retail | 2025 |
| ST Helens House Ltd | Hospitality | 2017 |
| ST Helens Mansions Limited | Households | 2002 |
| ST Helens Park Court, 133-135 Clarendon Road RTM Limited | Hospitality | 2012 |
| ST John’S Mews RTM Company Limited | Households | 2022 |
| ST Zandas Ltd | Wholesale & retail | 2023 |
| Stable Neighbours Ltd | Information & communication | 2026 |
| Stagedoor Southsea Ltd | Professional & scientific | 2017 |
| Stajo Property Limited | Real estate | 2015 |
| Stanley Street Freehold Limited | Households | 2022 |
| Star & Crescent Community Media CIC | Administrative & support | 2017 |
| Star Care Services Ltd | Health & social care | 2019 |
| Stardust Nails Studio Ltd | Other services | 2017 |
| Starfall Ltd | Extraterritorial | 2017 |
| Starlings Limited | Households | 2009 |
| Staylit Ltd | Wholesale & retail | 2025 |
| Steak Central Ltd | Hospitality | 2020 |
| Steel Solutions (South) Ltd | Construction | 2018 |
| Steel Some Space Ltd | Construction | 2016 |
| Stef Building Construction Ltd | Construction | 2019 |
| Stella K Studios Ltd | Arts & recreation | 2024 |
| Stellar Renew Solutions Ltd | Construction | 2025 |
| Stellenger Ltd | Information & communication | 2014 |
| Stephen Lodge Management Company (Southsea) Limited | Real estate | 2019 |
| Stephen Rigamoto Ltd | Professional & scientific | 2024 |
| Steven Stringer Photography Ltd | Professional & scientific | 2013 |
| Sticky BOY Limited | Hospitality | 2021 |
| Stingaciu Ioana Engineering Limited | Professional & scientific | 2015 |
| Stml Electrical Services Limited | Construction | 2023 |
| Stockbridge Capital Partners Limited | Extraterritorial | 2012 |
| Stone Red Construction Ltd | Construction | 2015 |
| Stonewharf Consulting Limited | Information & communication | 2025 |
| Stoney Beach Ltd | Other services | 2022 |
| Straindawg Promotions Ltd | Information & communication | 2024 |
| Strategic Business Advisor Ltd | Information & communication | 2019 |
| Street Pastors (Portsmouth) | Other services | 2007 |
| Streetvibes Barbers Ltd | Other services | 2024 |
| Streetworks Solutions Ltd | Construction | 2025 |
| Strivo Ltd | Administrative & support | 2026 |
| Strong Island Clothing Ltd | Wholesale & retail | 2015 |
| Strong Island Construction Ltd | Construction | 2020 |
| Strong Island Limited | Information & communication | 2011 |
| Structure Building Services Ltd | Construction | 2015 |
| Studio 108 Southsea Ltd | Education | 2025 |
| Studio 22:22 Ltd | Professional & scientific | 2011 |
| Studio B Southsea Ltd | Education | 2021 |
| Studyanalyst Ltd | Information & communication | 2025 |
| Sturgess Electrical Services Ltd | Construction | 2024 |
| Stylin Ltd | Wholesale & retail | 2025 |
| Suits U Cleaning Services Ltd | Other services | 2015 |
| Suits U Gardening & Clearance Ltd | Other services | 2017 |
| Suits U Painting and Decorating Ltd | Construction | 2021 |
| Suits U Property Maintenance Ltd | Other services | 2015 |
| Sultan Mini Market Ltd | Wholesale & retail | 2023 |
| Summax Limited | Professional & scientific | 2015 |
| Summit Shield Roofing Limited | Construction | 2026 |
| Sunbed Group Ltd | Other services | 2025 |
| Sunna (Portsmouth) Ltd | Wholesale & retail | 2025 |
| Super Happy Wing Limited | Professional & scientific | 2016 |
| Super Motion Collective Limited | Information & communication | 2025 |
| Superior Resource Services Ltd | Hospitality | 2011 |
| Sushi Mann Inn Ltd | Hospitality | 2026 |
| Sushi NO 9 Limited | Hospitality | 2021 |
| Sussex Court Management Company (Southsea) Limited | Extraterritorial | 1998 |
| Sussex Finance Ltd | Financial services | 2024 |
| Sustainable Conservation Trust | Real estate | 2020 |
| Sustainsage Group Ltd | Professional & scientific | 2023 |
| Suvi Property Ltd | Real estate | 2025 |
| Swami Shriji Convenience Store Limited | Wholesale & retail | 2013 |
| Swan Recruitment Holdings Limited | Financial services | 2025 |