| Southern Roofing Specialists Ltd | Construction | 2021 |
| Southern Ropes UK Ltd | Manufacturing | 2006 |
| Southern Sewing & Upholstery Services Ltd | Manufacturing | 2014 |
| Southern Skill Craft Ltd | Construction | 2014 |
| Southern Steam Services Ltd | Professional & scientific | 2022 |
| Southern Storage Solutions Limited | Other services | 2002 |
| Southern Structural Limited | Construction | 2020 |
| Southern Structural Surveys Limited | Professional & scientific | 2019 |
| Southern Surveying Services (2006) Limited | Other services | 2006 |
| Southern Surveying Services Limited | Construction | 2002 |
| Southern Tank Services Limited | Administrative & support | 2002 |
| Southern Technical Training Centre Ltd | Administrative & support | 2017 |
| Southern Track Resources Limited | Administrative & support | 2025 |
| Southern Transfers Ltd | Transport & logistics | 2023 |
| Southern Travel Group Ltd | Transport & logistics | 2026 |
| Southern Vcse Collaborative | Health & social care | 2026 |
| Southern Vehicle Services Ltd | Wholesale & retail | 2026 |
| Southern Vipers Ltd | Arts & recreation | 2016 |
| Southern Wave Property Developments Ltd | Real estate | 2023 |
| Southern Wetrooms Ltd | Construction | 2020 |
| Southern Window Services Ltd | Construction | 2010 |
| Southernvault Ltd | Wholesale & retail | 2026 |
| Southgate & Sterling Ltd | Wholesale & retail | 2014 |
| Southley Properties Limited | Real estate | 1997 |
| Southnewton Holdings Ltd | Real estate | 2024 |
| Southpoint Accountants Limited | Professional & scientific | 2026 |
| Southpoint Films Ltd | Information & communication | 2013 |
| Southport Transport Ltd | Transport & logistics | 2025 |
| Southsea Cars Ltd | Wholesale & retail | 2023 |
| Southsea Coliving Ltd | Real estate | 2019 |
| Southsea Fitness Limited | Wholesale & retail | 2013 |
| Southsea Village (NO.2) Limited | Real estate | 2024 |
| Southsea Village (NO.3) Limited | Real estate | 2024 |
| Southsea Village (NO.4) Limited | Real estate | 2024 |
| Southsea Village (NO.5) Limited | Real estate | 2024 |
| Southsea Village Limited | Real estate | 2021 |
| Southside Car Audio Limited | Wholesale & retail | 2005 |
| Southside Hire Ltd | Transport & logistics | 2024 |
| Southside INK Tattoo Studio Ltd | Other services | 2024 |
| Southside Travel Ltd | Transport & logistics | 2023 |
| Southstar Solutions Ukeig | | 2013 |
| Southtax Southampton Taxi Ltd | Administrative & support | 2021 |
| Southvale Care Ltd | Health & social care | 2019 |
| Southvale Driving School Ltd | Education | 2024 |
| Southways Property Limited | Real estate | 2021 |
| Southwell Lettings Ltd | Real estate | 2020 |
| Southwest Cradles (UK) Limited | Construction | 2012 |
| Southwestsensor Limited | Manufacturing | 2015 |
| Sovenia Ltd | Wholesale & retail | 2025 |
| Soveram Ltd | Information & communication | 2021 |
| Sovereign Court Residents Association (Southampton) Limited | Real estate | 1994 |
| Sovereign Lighting Limited | Manufacturing | 1993 |
| Sovereign Plus Resourcing Limited | Administrative & support | 2022 |
| Sovereign Stone Radiators Ltd | Other services | 2020 |
| Sowave Ltd | Information & communication | 2005 |
| Soya UK Limited | Agriculture & fishing | 2000 |
| Sozah Portfolio Management Ltd | Real estate | 2021 |
| SP Drive Ltd | Transport & logistics | 2025 |
| SP Systems & Technology Ltd | Information & communication | 2026 |
| SP Tyres 2U Ltd | Wholesale & retail | 2023 |
| Space Accounting Ltd | Professional & scientific | 2025 |
| Space AI Technology UK Ltd | Wholesale & retail | 2024 |
| Space Qube Ltd | Administrative & support | 2013 |
| Spacechain Residents Management Limited | Households | 1988 |
| Spacek Tech Ltd | Wholesale & retail | 2024 |
| Spaceway Projects Limited | Professional & scientific | 1992 |
| Spaceway South Limited | Construction | 1990 |
| Spacey Consulting Limited | Extraterritorial | 2018 |
| SPAID7 Retail Ltd | Wholesale & retail | 2023 |
| Spake Lets Ltd | Hospitality | 2019 |
| Spakle Cleaning Service Ltd | Administrative & support | 2025 |
| Spalding Fitness Coaching Ltd | Other services | 2022 |
| Spanner in the Works Ltd | Information & communication | 2005 |
| Spannertech Ltd | Wholesale & retail | 2016 |
| Spaqua Ltd | Manufacturing | 2025 |
| Sparemach Ltd | Wholesale & retail | 2024 |
| Sparesparts Ltd | Wholesale & retail | 2016 |
| Spark Home Improvements Ltd | Administrative & support | 2025 |
| Spark Security Services Ltd | Administrative & support | 2011 |
| Spark-Ease Services Ltd | Construction | 2021 |
| Sparkcards Ltd | Wholesale & retail | 2026 |
| Sparkle & Sage Limited | Health & social care | 2022 |
| Sparkle Aesthetics and Beauty Ltd | Other services | 2024 |
| Sparkle and Shine Eastleigh Commercial Cleaning Limited | Administrative & support | 2025 |
| Sparkle Cleaning Servicess Ltd | Administrative & support | 2025 |
| Sparkling 32 Ltd | Health & social care | 2024 |
| Sparkling Events Hampshire Limited | Hospitality | 2019 |
| Sparkling Gems Clean Ltd | Administrative & support | 2025 |
| Sparkling Staff Recruitment Ltd | Health & social care | 2021 |
| Sparks Commercial Holdings Limited | Financial services | 2017 |
| Sparks Commercial Services Limited | Wholesale & retail | 1998 |
| Sparks Commercials Exeter Limited | Wholesale & retail | 2022 |
| Sparks Commercials Poole Ltd | Wholesale & retail | 2011 |
| Sparks Commercials Portsmouth Limited | Wholesale & retail | 1999 |
| Sparks Commercials Swindon Limited | Wholesale & retail | 1987 |
| Sparkworks Energy Ltd | Construction | 2023 |
| Sparky Renovations Ltd | Construction | 2024 |
| Sparkys & Co (Hampshire) Ltd | Construction | 2014 |
| Sparkys & Hutch Electrical Limited | Construction | 2019 |
| Sparrow Joinery Ltd | Construction | 2011 |