| Software Testing House Ltd | Information & communication | 2020 |
| Sohail Salam Limited | Health & social care | 2013 |
| Soho Jesmond Ltd | Real estate | 2022 |
| Soho Securities Limited | Financial services | 2024 |
| SOHO4U Ltd | Hospitality | 2025 |
| SOL Stock Limited | Wholesale & retail | 2009 |
| SOL2O Limited | Construction | 2006 |
| Solana Properties Ltd | Real estate | 2018 |
| Solar Capture Technologies Limited | Manufacturing | 2011 |
| Solar Savvy Limited | Construction | 2025 |
| Solar Scale Marketing UK Ltd | Wholesale & retail | 2026 |
| Solar Tuition Ltd | Education | 2022 |
| Solar XYZ LLP | | 2007 |
| Solareast UK Limited | Construction | 2021 |
| Solarfold Holdings Limited | Manufacturing | 2012 |
| Solarhotty Ltd | Manufacturing | 2016 |
| Solaris Breaks Ltd | Hospitality | 2019 |
| Solaris Marketing Limited | Professional & scientific | 2025 |
| Solarlake Limited | Real estate | 2006 |
| Solas Aesthetics Limited | Health & social care | 2026 |
| Solehawk Limited | Health & social care | 1989 |
| Solent Blue Line Limited | Professional & scientific | 1987 |
| Solenta LLP | | 2025 |
| Solera Trading Limited | Wholesale & retail | 2022 |
| Solid Core Door Limited | Manufacturing | 2022 |
| Solid Tyre Disposals Limited | Water & waste | 2016 |
| Solidarity Farm CIC | Education | 2022 |
| Solidkit Ltd | Manufacturing | 2015 |
| Solnet AI Ltd | Information & communication | 2026 |
| Solnet World Ltd | Extraterritorial | 2026 |
| Solomons Carpets Limited | Professional & scientific | 1998 |
| Solstice Reporting Limited | Health & social care | 2019 |
| Soluna Collective Ltd | Professional & scientific | 2025 |
| Solution 13 Ltd | Information & communication | 2025 |
| Solution Performance Group Ltd | Administrative & support | 2016 |
| Solution Performance Resourcing Ltd | Administrative & support | 2021 |
| Solution Performance Software Ltd | Information & communication | 2021 |
| Solution Sense Limited | Households | 1995 |
| Solutions for Families Ltd | Health & social care | 2024 |
| Solutions for Trade Staff Ltd | Administrative & support | 2025 |
| Solutions UK Distribution Limited | Wholesale & retail | 2016 |
| Solveitquick Limited | Wholesale & retail | 2025 |
| Soma Praxis Ltd | Health & social care | 2025 |
| Somal Dental Limited | Health & social care | 2023 |
| Somal Family Properties Limited | Real estate | 2024 |
| Something Sweet and Savoury Ltd | Hospitality | 2013 |
| Sondy Media Ltd | Information & communication | 2025 |
| Sonero Tynemouth Limited | Hospitality | 2013 |
| Sonex Trading Ltd | Wholesale & retail | 2019 |
| Sonia Parcelnet Ltd | Transport & logistics | 2025 |
| Sonias Distribution Ltd | Transport & logistics | 2025 |
| Sonictek Limited | Administrative & support | 2006 |
| Sonna Food Store Ltd | Wholesale & retail | 2025 |
| Sonnetry Ltd | Wholesale & retail | 2025 |
| Sonoscan NDT Ltd | Other services | 2025 |
| Sons of Adonis Ltd | Wholesale & retail | 2019 |
| Sonus (Holdings) Limited | Financial services | 2020 |
| Soothe Ocular Spa Limited | Wholesale & retail | 2023 |
| Sophie Elaine Taylor Limited | Hospitality | 2019 |
| Sophie Says Limited | Information & communication | 2020 |
| Sophie Stevens Property Developments Ltd | Real estate | 2021 |
| Sopost Limited | Information & communication | 2012 |
| Sora Health Limited | Health & social care | 2024 |
| Sorella Rental Limited | Real estate | 2016 |
| Sorted PR Limited | Professional & scientific | 2010 |
| Soul at Play Ltd | Arts & recreation | 2024 |
| Soul Food Jesmond Ltd | Hospitality | 2026 |
| Soul Forge Ltd | Wholesale & retail | 2018 |
| Soul Hairdressing Limited | Other services | 2006 |
| Soul JAM Events Ltd | Arts & recreation | 2019 |
| Soul Rebel Limited | Wholesale & retail | 2021 |
| Soumya Consultancy Limited | Health & social care | 2016 |
| Sound Mind & Body Limited | Health & social care | 2002 |
| Sound, Food and Drink Limited | Hospitality | 2019 |
| Soundproof Audio Ltd | Manufacturing | 2023 |
| Sounds Alarming NE Ltd | Wholesale & retail | 2025 |
| Sounds Alarming North East Limited | Wholesale & retail | 2011 |
| Sounds of Joy CIC | Information & communication | 2025 |
| Soundtracks Ltd | Arts & recreation | 2020 |
| Soup "a" Shake Limited | Wholesale & retail | 2007 |
| Sourced Luxury Ltd | Wholesale & retail | 2022 |
| Sourceguardian Ltd | Administrative & support | 2005 |
| South Cambridgeshire Investments Holdings Limited | Administrative & support | 2020 |
| South Cambridgeshire Projects LLP | | 2020 |
| South Durham Health C.I.C. | Health & social care | 2011 |
| South Durham Primary Care Ltd | Extraterritorial | 2015 |
| South East Powergrid Limited | Extraterritorial | 2011 |
| South Eastern Powergrid Limited | Extraterritorial | 2011 |
| South Haven Management Limited | Real estate | 2004 |
| South Lakeland Group Limited | Professional & scientific | 2006 |
| South Lakeland Parks Limited | Hospitality | 1994 |
| South Lodge Wood Management Company Limited | Real estate | 2011 |
| South Meadow Rennington Management Company Limited | Households | 2019 |
| South Powergrid Limited | Extraterritorial | 2011 |
| South Shields (Biddick Green) Management Company Limited | Real estate | 2013 |
| South Shields Surf CIC | Education | 2019 |
| South Shore Phase 2 (Blyth) Management Company Limited | Real estate | 2013 |
| South Tyneside Offshore Medicals Ltd | Health & social care | 2026 |
| South West Powergrid Limited | Extraterritorial | 2011 |
| South Western Powergrid Limited | Extraterritorial | 2011 |