| SK Plumbing & Bathrooms Ltd | Construction | 2025 |
| SK Pro Electrical Ltd | Construction | 2019 |
| Skate & Surf Supply Network Limited | Wholesale & retail | 2022 |
| Skawi Ltd | Administrative & support | 2007 |
| Skiin Sanctuary Ltd | Other services | 2025 |
| Skim London Limited | Professional & scientific | 2009 |
| Skinbay Aesthetics Ltd | Other services | 2022 |
| Skincareexpress Beauty Products Ltd | Other services | 2011 |
| Skinfinity Aesthetics & Education Ltd | Health & social care | 2024 |
| Skmc Property Investment Limited | Real estate | 2026 |
| SKR Housing Ltd | Real estate | 2023 |
| Skri Ltd | Real estate | 2025 |
| Skyblue Building Maintenance Limited | Construction | 2024 |
| Skydan Ltd | Transport & logistics | 2023 |
| Skyline Management (Stevenage) Limited | Households | 2015 |
| Skyline Source Limited | Real estate | 2024 |
| Skyline Taxis Limited | Transport & logistics | 2013 |
| Skylinecreate Limited | Education | 2018 |
| Skylluxe Glow MED Spa Limited | Education | 2025 |
| Skypoint Ltd | Professional & scientific | 2004 |
| SL Auto Repairs Limited | Wholesale & retail | 2025 |
| SL Legal and Business Consultants Ltd | Professional & scientific | 2022 |
| Slae Ltd | Financial services | 2023 |
| Slartibartfast Ltd | Professional & scientific | 2017 |
| Slcms Limited | Professional & scientific | 2011 |
| Sleazy Rider Limited | Wholesale & retail | 2023 |
| Sleek Cheek Ltd | Health & social care | 2024 |
| Sleek Cheek Properties Ltd | Real estate | 2026 |
| Slice Editing Limited | Information & communication | 2023 |
| SLJ Investments Ltd | Real estate | 2023 |
| Slough Used Cars Ltd | Wholesale & retail | 2019 |
| SLÓ Living Ltd | Wholesale & retail | 2025 |
| SM Consortium Limited | Hospitality | 2020 |
| SM Simply Accounting Limited | Professional & scientific | 2026 |
| Small Cat Ltd. | Information & communication | 2021 |
| Smart Alterations Ltd | Wholesale & retail | 2025 |
| Smart Clean Laundry Limited | Other services | 2017 |
| Smart Home Enterprises Limited | Construction | 2017 |
| Smart N FIX Ltd | Wholesale & retail | 2024 |
| Smart Student Solutions Ltd | Education | 2025 |
| Smart Wear Outfits Limited | Wholesale & retail | 2015 |
| Smart Web Centre Limited | Information & communication | 2002 |
| Smart Worldwide Investments Ltd | Financial services | 2021 |
| Smartey Electrical Ltd | Construction | 2022 |
| Smash Burger Bros Ltd | Hospitality | 2023 |
| SMC Transport Services Ltd | Transport & logistics | 2019 |
| SME Finance Managers Ltd | Professional & scientific | 2003 |
| Smeaton Consultancy Services Ltd | Administrative & support | 2017 |
| Smita Limited | Health & social care | 2025 |
| Smith & Sons Talent Connect Ltd | Administrative & support | 2024 |
| Smith and Aplin Properties Ltd | Real estate | 2018 |
| Smiths Maintenance Ltd | Construction | 2024 |
| SMJ Products Ltd | Wholesale & retail | 2019 |
| SML Logistics Ltd | Transport & logistics | 2024 |
| Smok'N Greek BBQ Limited | Hospitality | 2018 |
| Smokey Steve's Ltd | Hospitality | 2026 |
| Smoky Chef Limited | Hospitality | 2025 |
| Smood Entertainment Ltd. | Arts & recreation | 2021 |
| Smyths Print and Design Limited | Manufacturing | 2017 |
| SN Home Maintenance Service Ltd | Construction | 2024 |
| Snape Industries Limited | Professional & scientific | 2025 |
| Sniper Security Limited | Construction | 2019 |
| Snow Design Limited | Professional & scientific | 2010 |
| Snowfield Properties Ltd | Real estate | 2021 |
| SO Coaching Consulting Services Ltd | Professional & scientific | 2023 |
| SO Corporate Ltd | Arts & recreation | 2024 |
| SO Cosy Ltd | Wholesale & retail | 2011 |
| SO Discos Entertainment Ltd | Arts & recreation | 2022 |
| SO Salsa 23 Limited | Hospitality | 2017 |
| SO Salsa Bold Street 23 Limited | Other services | 2024 |
| SO Salsa Castle Street 23 Limited | Hospitality | 2021 |
| SOC Orthodontics Limited | Health & social care | 2020 |
| Softland PAD Sector Limited | Other services | 2024 |
| Sola Holdings Limited | Financial services | 2023 |
| Solar Surplus Ltd | Wholesale & retail | 2018 |
| Soldby Services Limited | Professional & scientific | 2014 |
| Solidus Independent Estate Planning Ltd | Professional & scientific | 2009 |
| Solis Media Group Ltd | Information & communication | 2018 |
| Solnet Consultants Limited | Professional & scientific | 2022 |
| Solodany Ltd | Transport & logistics | 2015 |
| Soluify Limited | Information & communication | 2024 |
| SOLVIX1 Ltd | Construction | 2026 |
| Somani Holdings Limited | Hospitality | 2007 |
| Somani Hotels (Croydon) Limited | Hospitality | 2015 |
| Somani Hotels (Stevenage) Limited | Hospitality | 2007 |
| Somani Portfolio Limited | Real estate | 2015 |
| Somarq Services Limited | Transport & logistics | 2025 |
| Something Happening Ltd | Professional & scientific | 2026 |
| Sona Estates Limited | Real estate | 2018 |
| Sonikk Limited | Information & communication | 2013 |
| Sonnys Super Solutions Ltd | Manufacturing | 2025 |
| Sontec Electrical Services Limited | Construction | 2003 |
| Sontec Plant Hire Limited | Administrative & support | 2014 |
| Sophia' S Designs Ltd | Other services | 2006 |
| Sophie Derrick Art Limited | Wholesale & retail | 2024 |
| Sophie Gold Limited | Health & social care | 2016 |
| Sophisticated Structures Limited | Professional & scientific | 2021 |
| Sophos Consultancy Limited | Arts & recreation | 2025 |
| Sophtec Consulting Limited | Information & communication | 2007 |
| Soul Tonic Limited | Arts & recreation | 2015 |