| South & North Development Ltd | Real estate | 2025 |
| South Asia Future Forum | Administrative & support | 2017 |
| South City Heating Limited | Energy | 2012 |
| South Croydon Properties Limited | Real estate | 2020 |
| South Croydon Tyres & Services Centre Ltd | Wholesale & retail | 2024 |
| South East (Wholesale) Bakery Ltd | Manufacturing | 2007 |
| South East Bakery Ltd | Manufacturing | 2022 |
| South East Kitchen Fitters Ltd | Manufacturing | 2022 |
| South Eastern Coin Equipment Limited | Real estate | 1974 |
| South END 99 Plus Ltd | Wholesale & retail | 2022 |
| South END Food Centre Ltd | Wholesale & retail | 2019 |
| South END Road Management Company Limited | Households | 2020 |
| South Godstone Garage Limited | Real estate | 1978 |
| South Hermitage Management Company Limited | Households | 1995 |
| South House Management Limited | Households | 1991 |
| South Kirkby Healthcare LLP | | 2011 |
| South London Drainage & Plumbing Limited | Construction | 2015 |
| South London Fencing Ltd | Construction | 2015 |
| South London Hardwoods Limited | Professional & scientific | 1996 |
| South London Lettings Limited | Real estate | 2017 |
| South London Management Limited | Real estate | 2013 |
| South London Properties (SLP) Limited | Real estate | 2011 |
| South London Repair Limited | Other services | 2015 |
| South Motorbikes Ltd | Wholesale & retail | 2025 |
| South Norwood & Woodside Community Association | Health & social care | 2010 |
| South Norwood Community Festival CIC | Administrative & support | 2024 |
| South One Limited | Construction | 2021 |
| South Spice Group Ltd | Hospitality | 2025 |
| South Thames GAS Limited | Construction | 2005 |
| South West Cash & Carry Ltd | Wholesale & retail | 2026 |
| South West London Law Centres | Professional & scientific | 2004 |
| Southacre Administration Limited | Real estate | 2001 |
| Southacre Freehold Company Limited | Real estate | 2003 |
| Southbridge Pizza Ltd | Hospitality | 2024 |
| Southbridge Road Hand Car Wash Ltd | Administrative & support | 2022 |
| Southdown House Management (Harpenden) Limited | Households | 1974 |
| Southend Grange Limited | Hospitality | 2026 |
| Southend Rochford Care Services Limited | Health & social care | 2008 |
| Southern Angels Ltd | Health & social care | 2025 |
| Southern Business Networks Limited | Construction | 1996 |
| Southern Cooling Services Ltd | Construction | 2018 |
| Southern Delight Limited | Wholesale & retail | 2018 |
| Southern Industrial Pipeline Services Limited | Construction | 1999 |
| Southern Mechanical Services Limited | Construction | 2007 |
| Southern Property Kent Limited | Real estate | 2017 |
| Southernceilings Ltd | Other services | 2017 |
| Southerngate Investments Ltd | Professional & scientific | 2017 |
| Southgate Central Residents Management Company Limited | Households | 2004 |
| Southgate Protection CIC | Administrative & support | 2025 |
| Southpark (Macclesfield) Management Company Limited | Households | 2007 |
| Southside (Narborough Road NO. 1) Management Company Limited | Households | 2004 |
| Souththames Housing Limited | Real estate | 2013 |
| Sovereign Cars Retail Ltd | Wholesale & retail | 2010 |
| Sovereign Court (Victoria Villas) Freehold Limited | Households | 2000 |
| Sovereign Drive Exclusives Ltd | Administrative & support | 2024 |
| Sovereign Gate (Wembley) Management Limited | Households | 1992 |
| Sovereign Gate Residents Management Company Limited | Households | 2014 |
| Sovereign Place Kingston Upon Thames Management Company Limited | Households | 1996 |
| Sovereign Spaces Ltd | Administrative & support | 2025 |
| Sovereign Travel Ltd | Public administration | 2023 |
| Sowe's Electrical Engineering Services Ltd | Administrative & support | 2017 |
| SP & YP Limited | Wholesale & retail | 2020 |
| SP Business Solutions Limited | Professional & scientific | 2014 |
| SP Food and Events Ltd | Hospitality | 2025 |
| SP Newgate Limited | Real estate | 2023 |
| SP Steel Limited | Construction | 2024 |
| Spa Court (Morecambe) Management Company Limited | Households | 2017 |
| Spa Stop Limited | Other services | 2016 |
| Spac Logistics Limited | Transport & logistics | 2017 |
| Space & Star Ltd | Real estate | 2025 |
| Space Realtors Limited | Hospitality | 2024 |
| Spacelease Limited | Real estate | 2005 |
| Spacetech Solutions Limited | Information & communication | 2022 |
| Spain Daymsai Marine Bioscience Ltd | Administrative & support | 2023 |
| Spanish Green Horticultural Products Limited | Administrative & support | 2023 |
| Spargo Hair & Beauty Ltd | Other services | 2020 |
| Spargo Productions Limited | Arts & recreation | 2018 |
| Sparkbrook Enterprise Ltd | Wholesale & retail | 2004 |
| Sparke Cleaning Services Ltd | Administrative & support | 2025 |
| Sparker-One-Consulting Ltd | Professional & scientific | 2025 |
| Sparkfied Ltd | Wholesale & retail | 2024 |
| Sparkkin Ltd | Wholesale & retail | 2016 |
| Sparkline Enterprises Limited | Wholesale & retail | 2023 |
| Sparklyspacesolutions Ltd | Administrative & support | 2025 |
| Sparkz Technologies U.K. Ltd | Information & communication | 2022 |
| Sparrow Food and Wine Ltd | Wholesale & retail | 2025 |
| Sparrow Investment Property Limited | Real estate | 2020 |
| Spartan Guard Ltd | Construction | 2026 |
| Spatia Limited | Professional & scientific | 2013 |
| Spaza Global Ltd | Wholesale & retail | 2022 |
| Spdx Limited | Health & social care | 2021 |
| Spearmoor Limited | Real estate | 1991 |
| Spearshaw Ltd | Manufacturing | 2022 |
| Special African Foods Ltd | Wholesale & retail | 2025 |
| Specialist Decorating Contractors Limited | Construction | 2012 |
| Specialist Plumbing Ltd | Construction | 2024 |
| Specialist Urology Services Limited | Health & social care | 2013 |
| Speckles Day Nurseries Ltd | Health & social care | 2018 |
| Spector Investments Limited | Real estate | 2020 |
| Spector Properties Ltd | Real estate | 2024 |