| Simon Wilkinson Surveyors Limited | Professional & scientific | 2017 |
| Simple Coaching Limited | Arts & recreation | 2023 |
| Simple EPR Limited | Professional & scientific | 2023 |
| Simple Scanning Solutions Limited | Health & social care | 2016 |
| Simpli Baked UK Limited | Extraterritorial | 2020 |
| Simply Change Ltd | Information & communication | 2016 |
| Sinaqua Systems Limited | Professional & scientific | 2008 |
| Sine Wave Surrey Limited | Other services | 2018 |
| Singh Sons Builders Ltd | Construction | 2025 |
| Single Media Ltd | Information & communication | 2020 |
| SIP Services Ltd | Professional & scientific | 2016 |
| SIR Robert Fossett's Circus Limited | Arts & recreation | 1990 |
| Sirgee Ltd | Information & communication | 2022 |
| Site Audits Limited | Professional & scientific | 2000 |
| SJ International Associate Ltd | Hospitality | 2022 |
| SJ Paint Ltd | Wholesale & retail | 2022 |
| SJB Properties (Banbury) Limited | Real estate | 2013 |
| SJG Management Limited | Professional & scientific | 2009 |
| SJN Pile (Farming) Ltd | Agriculture & fishing | 2022 |
| SJP Banbury Ltd | Education | 2024 |
| SK Technical Engineering Ltd | Professional & scientific | 2026 |
| Skathefyre Ltd | Professional & scientific | 2020 |
| Skeath Allan Limited | Real estate | 2023 |
| Skerrols House Limited | Hospitality | 2013 |
| SKG Nicklin Ltd | Professional & scientific | 2026 |
| Skin Design Services Ltd | Professional & scientific | 2019 |
| SKL Food Ltd | Hospitality | 2024 |
| Skowyk Ltd | Wholesale & retail | 2016 |
| Skukan Ltd | Professional & scientific | 2024 |
| Skyline Havens Ltd | Hospitality | 2025 |
| Slash Projects Limited | Other services | 2009 |
| Slash Property Limited | Real estate | 2017 |
| Slate Innovations Limited | Information & communication | 2020 |
| Sleep Easy Hotels Ltd | Hospitality | 2019 |
| Sliced 3D Limited | Other services | 2023 |
| SLK Investment Properties Limited | Real estate | 2024 |
| SLP Advisors Limited | Professional & scientific | 2025 |
| SLS Garage Banbury Limited | Other services | 2024 |
| SM Foods 1 Ltd | Hospitality | 2017 |
| SM Gull Property Ltd | Real estate | 2025 |
| SM Modlen Garage Ltd | Wholesale & retail | 2019 |
| SMA Solar UK Ltd. | Manufacturing | 2010 |
| Smack Group Limited | Administrative & support | 2023 |
| Smart Home Design Limited | Construction | 2018 |
| Smart Housing Ltd | Real estate | 2016 |
| Smart Polish Ltd | Wholesale & retail | 2016 |
| Smart Railway Power Limited | Information & communication | 2025 |
| Smart World Vends Ltd | Wholesale & retail | 2026 |
| Smartex Logistics Ltd | Transport & logistics | 2022 |
| Smartipants Ironing Service Limited | Other services | 2016 |
| Smash Cambridge Limited | Hospitality | 2024 |
| SMB Consulting Services Limited | Professional & scientific | 2002 |
| SMB GAS and Heating Ltd | Construction | 2016 |
| Smite&Bite Ltd | Hospitality | 2026 |
| Smith and Clay Limited | Manufacturing | 2006 |
| Smith Farm Consulting Ltd | Wholesale & retail | 2018 |
| Smith of Bloxham Ltd | Agriculture & fishing | 2026 |
| Smiths of Bloxham Farms Limited | Extraterritorial | 2014 |
| Smiths of Bloxham Ltd | Wholesale & retail | 2023 |
| Smnj Consulting (Oxfordshire) Ltd | Professional & scientific | 2024 |
| Smokers F.G Ltd | Wholesale & retail | 2021 |
| Smolbrain Ltd | Information & communication | 2025 |
| Smova Studios Limited | Information & communication | 2025 |
| SMR Projects Limited | Construction | 2001 |
| SMW Design Services Limited | Professional & scientific | 2023 |
| SN Services(Gb) Limited | Administrative & support | 2010 |
| SNA Construct Ltd | Construction | 2025 |
| Snapdragon Marketing Limited | Extraterritorial | 2012 |
| SNG Estates Ltd | Real estate | 2023 |
| Snooz ‘N Slumber Ltd | Wholesale & retail | 2025 |
| Snowline Media Ltd | Administrative & support | 2013 |
| SO Souk LLP | | 2017 |
| Socius Associates Limited | Other services | 2014 |
| Soft Track Limited | Wholesale & retail | 2018 |
| Soho Recruitment Limited | Construction | 2023 |
| Solart Ltd | Information & communication | 2011 |
| Solenet Global Limited | Information & communication | 2020 |
| Soleraduica Property Services Limited | Real estate | 2019 |
| Solid Property Solutions Ltd | Construction | 2026 |
| Solidleaf Limited | Financial services | 2020 |
| Solidus Construction Banbury Ltd | Construction | 2013 |
| Solotransporter Ltd | Manufacturing | 2016 |
| Solus Lighting Limited | Manufacturing | 1978 |
| Solutions Driven Consulting Ltd | Professional & scientific | 2023 |
| Somerton Security Services Ltd | Administrative & support | 2015 |
| Something to Sell Reselling LLP | | 2024 |
| Sonata Collective Limited | Education | 2026 |
| Sonavahal Limited | Information & communication | 2024 |
| Sonedd Engineering (UK) Limited | Energy | 2000 |
| Sonic 2025 Limited | Transport & logistics | 2025 |
| Sophie Boss Ltd | Transport & logistics | 2023 |
| Sounds Write Music Limited | Arts & recreation | 2018 |
| Soundwave Audio Holdings Limited | Administrative & support | 2014 |
| Soundwave Audio Limited | Administrative & support | 2013 |
| South Hill Farm Consultancy Ltd | Professional & scientific | 2014 |
| South London Cafe T/A Grillerz Ltd | Hospitality | 2021 |
| South Northants Home Care Ltd | Health & social care | 2015 |
| Southam 2024 Ltd | Real estate | 2024 |
| Sovereign Ferries Limited | Transport & logistics | 2014 |
| Sovereign Wharf Limited | Transport & logistics | 2014 |