| Skittles Community Shop CIC | Wholesale & retail | 2022 |
| Skive & Stitch Belt Co Ltd | Wholesale & retail | 2025 |
| Sklserenitycare Limited | Health & social care | 2026 |
| Skootin Ltd | Information & communication | 2026 |
| SKP Healthcare Limited | Wholesale & retail | 2023 |
| Skqt Ltd | Administrative & support | 2016 |
| Skrap Ltd | Water & waste | 2017 |
| Skratta Limited | Information & communication | 2017 |
| Sksira Ltd | Health & social care | 2023 |
| Sky Birds Limited | Wholesale & retail | 2002 |
| Sky Cars Northampton Ltd | Transport & logistics | 2017 |
| Sky Deliver Ltd | Wholesale & retail | 2025 |
| Sky Lenz Ltd | Professional & scientific | 2025 |
| Sky Pet Products Ltd | Wholesale & retail | 2008 |
| Sky Power Plants Limited | Manufacturing | 2023 |
| Sky Propertyxpert Ltd | Real estate | 2024 |
| Sky Techno Limited | Wholesale & retail | 2014 |
| Sky Valets Northampton Ltd | Other services | 2019 |
| Sky X Cars Limited | Transport & logistics | 2023 |
| Sky's the Limit Logistics Services Ltd | Transport & logistics | 2021 |
| Skyace Telecom Limited | Information & communication | 2023 |
| Skybound Games UK Limited | Information & communication | 2018 |
| Skycrest Ltd | Real estate | 2024 |
| Skye Recruitment Ltd | Administrative & support | 2015 |
| Skye Recruitment Services Ltd | Administrative & support | 2023 |
| Skyguard Roofing Services LLP | | 2023 |
| Skylark Management Company (Swinford) Limited | Households | 2021 |
| Skylight Living Ltd | Real estate | 2024 |
| Skylimit Projects Ltd | Hospitality | 2022 |
| Skyline IND Limited | Professional & scientific | 2025 |
| Skynar Limited | Wholesale & retail | 2023 |
| Skynut Rail Engineering Limited | Construction | 2026 |
| Skypropertyxperts Holdings Ltd | Real estate | 2025 |
| Skyrise Builders Ltd | Construction | 2025 |
| Skyscape Developments & Investments Ltd | Real estate | 2014 |
| Skyscraper Publications Limited | Information & communication | 2013 |
| SL Commerce Ltd | Wholesale & retail | 2020 |
| SLA Medics Limited | Health & social care | 2020 |
| Slad Investments Ltd | Financial services | 2021 |
| Slad Limited | Financial services | 2018 |
| Slake Recovery Ltd | Other services | 2026 |
| Slav Express Limited | Transport & logistics | 2025 |
| Slavik Limited | Wholesale & retail | 2024 |
| Slavol Ltd | Administrative & support | 2019 |
| SLD Scaffolding Limited | Construction | 2025 |
| Slicknomad Ltd | Wholesale & retail | 2025 |
| Sline Consultancy Ltd | Professional & scientific | 2025 |
| Slira Technology & Services Ltd | Administrative & support | 2025 |
| SLK Audio Limited | Manufacturing | 2002 |
| SLL Construction Ltd | Construction | 2020 |
| Sloane Helicopters Limited | Transport & logistics | 1989 |
| Sloane Industries Ltd | Administrative & support | 2022 |
| Sloanes of Uppingham Hair and Beauty Salon Limited | Other services | 2019 |
| Sloped Limited | Wholesale & retail | 2023 |
| SLP UK Services Limited | Real estate | 2023 |
| SLR Care Limited | Health & social care | 2017 |
| SLR Property Ltd | Real estate | 2020 |
| SLR Training & Consultancy Ltd | Real estate | 2023 |
| SM Accounts & Payroll Ltd | Professional & scientific | 2021 |
| SM Building Works Ltd | Construction | 2021 |
| SM Constructors Ltd | Construction | 2024 |
| SM Creative Studio Ltd. | Wholesale & retail | 2023 |
| SM Delivery Ltd | Transport & logistics | 2018 |
| SM Developments Limited | Construction | 2002 |
| SM Logistics Services Ltd | Transport & logistics | 2020 |
| SM Parts Limited | Wholesale & retail | 2025 |
| SM Prime Property Limited | Real estate | 2025 |
| SM Project Management Services Ltd | Construction | 2017 |
| SM Properties UK Limited | Construction | 2003 |
| SM1 Print Studio Limited | Manufacturing | 2019 |
| Smaart Consultancy Ltd | Information & communication | 2013 |
| Smaddanki Ltd | Information & communication | 2025 |
| Small Business Infrastructure Services UK Ltd | Information & communication | 2010 |
| Small Giants Media Limited | Information & communication | 2020 |
| Small Wonders Day Nursery Ltd | Education | 2003 |
| Small Wonders Nursery Stamford Limited | Education | 2018 |
| Small World (London) Ltd | Professional & scientific | 1991 |
| Smart Acca Limited | Administrative & support | 2024 |
| Smart Access Solutions Ltd | Administrative & support | 2014 |
| Smart Animal Technologies Ltd | Information & communication | 2026 |
| Smart Conservatory Solutions Ltd | Construction | 2015 |
| Smart Decor Commercials Ltd | Construction | 2019 |
| Smart Dining Company Limited | Hospitality | 2020 |
| Smart Electrical Northants Ltd | Construction | 2022 |
| Smart Home & Conservatory Solutions Limited | Construction | 2025 |
| Smart Home Cover Ltd | Manufacturing | 2018 |
| Smart Living London Ltd | Administrative & support | 2018 |
| Smart Northampton Limited | Wholesale & retail | 2009 |
| Smart OPS Digital Ltd | Information & communication | 2026 |
| Smart Reporting Limited | Information & communication | 2021 |
| Smart Solutions (U.K.) Limited | Construction | 2015 |
| Smart Supplier Technologies Limited | Information & communication | 2025 |
| Smart Surface Ltd | Construction | 2025 |
| Smart Tech Secure Ltd | Administrative & support | 2024 |
| Smart UK Clothing Ltd | Wholesale & retail | 2019 |
| Smartace Ltd | Professional & scientific | 2017 |
| Smartchase Limited | Wholesale & retail | 2023 |
| Smartdrylining Ltd | Construction | 2022 |
| Smarter Coding Ltd | Information & communication | 2021 |
| Smarthaus Investments Limited | Construction | 2020 |