| Smartweeder Ltd | Other services | 2024 |
| Smash Physical Training Limited | Arts & recreation | 2020 |
| Smashing Sellways Ltd | Wholesale & retail | 2025 |
| Smashmed Limited | Education | 2016 |
| Smashmk Limited | Education | 2026 |
| Smat Infotech Limited | Information & communication | 2014 |
| SMB Autocare Limited | Wholesale & retail | 2019 |
| SMB Partners Ltd | Information & communication | 2007 |
| SMC Autos Limited | Manufacturing | 2014 |
| SMC Corporation (U.K.) Limited | Manufacturing | 1978 |
| SMC Driving Services Ltd | Transport & logistics | 2018 |
| SMC Fencing & Landscapes Ltd | Administrative & support | 2024 |
| SME IT Networks Limited | Information & communication | 2007 |
| Smeethy Limited | Wholesale & retail | 2021 |
| SMF Contracts and Services Ltd | Real estate | 2019 |
| SMH Housing Ltd | Real estate | 2020 |
| SMI Technology Europe Limited | Manufacturing | 2006 |
| Smile Diaries Ltd | Health & social care | 2025 |
| Smile Heathcare Ltd | Administrative & support | 2025 |
| Smilelux Limited | Health & social care | 2020 |
| Smiles Childcare/Childminding Ltd | Health & social care | 2020 |
| Smiles Investment Ltd | Real estate | 2025 |
| Smileverse Limited | Information & communication | 2023 |
| Smiley Snap Photography Ltd | Professional & scientific | 2025 |
| Smiley Whites Ltd | Other services | 2024 |
| Smistry Properties Ltd | Real estate | 2018 |
| Smith Aggregates & Builders Merchants Ltd | Mining & quarrying | 2016 |
| Smith Construction Group Limited | Mining & quarrying | 1994 |
| Smith Farming Limited | Agriculture & fishing | 2019 |
| Smith Group Holdings Limited | Construction | 2004 |
| Smith Jenkins (L&P) Limited | Real estate | 2017 |
| Smith Jenkins Ltd | Professional & scientific | 2012 |
| Smith Recycling (Milton Keynes) Limited | Water & waste | 2004 |
| Smith Recycling Holdings Limited | Water & waste | 2023 |
| Smith Roofing Specialists Ltd | Construction | 2024 |
| Smithreed Limited | Professional & scientific | 2004 |
| Smiths Court Property Management Limited | Households | 2015 |
| Smiths Electrical (MK) Ltd | Other services | 2012 |
| Smithwright Limited | Wholesale & retail | 2025 |
| Smithybrowns Limited | Hospitality | 2017 |
| SMK Conversions Limited | Construction | 2016 |
| SML IT Consultancy Services Limited | Information & communication | 2022 |
| Smmo Property Ltd | Real estate | 2021 |
| Smoke Craft UK Ltd | Wholesale & retail | 2025 |
| Smokey Joe's Vapes Co Limited | Wholesale & retail | 2024 |
| Smokinbutcher Ltd | Wholesale & retail | 2025 |
| Smooch Aesthetics Ltd | Health & social care | 2015 |
| Smooth Boost Limited | Hospitality | 2012 |
| Smooth International Limited | Wholesale & retail | 2025 |
| Smoothcart Limited | Wholesale & retail | 2024 |
| Smppc Limited | Professional & scientific | 2017 |
| SMR Catering Ltd | Hospitality | 2017 |
| SMR Festivals Limited | Arts & recreation | 2025 |
| SMS Engineering Ltd | Professional & scientific | 2020 |
| Smudgedpixels Limited | Administrative & support | 2026 |
| Smul UK Limited | Wholesale & retail | 2023 |
| SN Domains Ltd | Information & communication | 2008 |
| SN Innovation Trading Limited | Administrative & support | 2017 |
| SN1 & Co. Limited | Professional & scientific | 2024 |
| Snab Homes Limited | Real estate | 2022 |
| Snack AID Limited | Hospitality | 2012 |
| Snack Food Poco Loco UK Limited | Manufacturing | 2013 |
| Snack Hub Ltd | Hospitality | 2015 |
| Snackline Direct Limited | Wholesale & retail | 2005 |
| Snag Your Home Ltd | Construction | 2025 |
| Snanovate Ltd | Extraterritorial | 2019 |
| Snap Business Limited | Financial services | 2026 |
| Snap Finance Limited | Financial services | 2012 |
| Snap Finance UK (Group) Limited | Financial services | 2017 |
| Snap Line Limited | Financial services | 2025 |
| Snappy Crafts Ltd | Wholesale & retail | 2026 |
| SND Info Limited | Information & communication | 2022 |
| Snetor UK Limited | Wholesale & retail | 2012 |
| SNG Technologies Ltd | Information & communication | 2012 |
| Snif-Snax UK PRD Limited | Manufacturing | 2025 |
| Snikb Technologies Limited | Information & communication | 2023 |
| SNK Info Tech PVT Ltd | Information & communication | 2024 |
| SNL Investments Ltd | Real estate | 2010 |
| SNM Medical Services Ltd | Health & social care | 2019 |
| Snna IT Consulting UK Ltd | Information & communication | 2022 |
| Snna Trading Ltd | Wholesale & retail | 2025 |
| Snns Ltd | Information & communication | 2008 |
| Snohus Ltd | Construction | 2022 |
| Snowdon (Raunds) Limited | Real estate | 2015 |
| Snowdon (Ringstead) Ltd | Real estate | 2017 |
| Snowdon Bramley Road Limited | Real estate | 2016 |
| Snowdon Consultants Limited | Construction | 2016 |
| Snowdon Freeholds Limited | Real estate | 2007 |
| Snowdon Homes Ltd | Construction | 2014 |
| Snowdon Management Company Limited | Real estate | 2007 |
| Snowdrop Homes Ltd | Real estate | 2017 |
| Snowstorm (Holdings) Limited | Information & communication | 2020 |
| Snowstorm Technologies (UK) Ltd | Information & communication | 2019 |
| SNP Productions Limited | Information & communication | 1999 |
| Snpk Properties Limited | Real estate | 2018 |
| SNR Property Group Ltd | Real estate | 2026 |
| SNR Property Lets Limited | Real estate | 2017 |
| Snrm Limited | Manufacturing | 2008 |
| SNS Medical Ltd | Health & social care | 2021 |
| SNS Travel Service Ltd | Transport & logistics | 2025 |