| Steel Magnolia Limited | Real estate | 2021 |
| Steel Secure Ltd | Health & social care | 2018 |
| Steelberg 3178 Limited | Real estate | 2016 |
| Steelbrook Construction Ltd | Construction | 2014 |
| Steelwood Craft Ltd | Manufacturing | 2019 |
| Steeple Medical Services Limited | Health & social care | 2012 |
| Steff Design Limited | Construction | 2019 |
| Steffens Electrical Services Ltd | Administrative & support | 2001 |
| Stefmar Ltd | Wholesale & retail | 2018 |
| Steg Health Limited | Manufacturing | 2021 |
| Steinbeck Walk Management Company Limited | Households | 2016 |
| Stel Construction Ltd | Construction | 2022 |
| Stellar Business and Law Solutions Ltd | Transport & logistics | 2014 |
| Stellar Consultants Ltd | Information & communication | 2022 |
| Stellar Developments (UK) Limited | Construction | 2018 |
| Stellar Nova Ltd | Wholesale & retail | 2025 |
| Stellar Otidelis Holdings Ltd | Financial services | 2024 |
| Stellaria Real Estate Limited | Real estate | 2008 |
| Stellus Group Ltd | Information & communication | 2026 |
| Steltrat Aviation Engineering Limited | Manufacturing | 2026 |
| Stem Research Ltd | Professional & scientific | 2022 |
| Stemaco (RAW Materials) Limited | Wholesale & retail | 1982 |
| Stemax Consult Healthcare Services Limited | Health & social care | 2011 |
| Stemaxis Ltd | Professional & scientific | 2025 |
| Stemrooted Recruitment Limited | Administrative & support | 2025 |
| Sten Properties Ltd | Real estate | 2020 |
| Stenton Obhi Architects Ltd | Professional & scientific | 2009 |
| Step Above Stairs Ltd | Construction | 2023 |
| Step Realty Ltd | Real estate | 2025 |
| Step UP Creative Limited | Information & communication | 2023 |
| Stepfirst Limited | Other services | 2000 |
| Stephanie Romanow Jewellery Limited | Manufacturing | 2022 |
| Stephen & SON Gunmakers Ltd | Manufacturing | 2011 |
| Stephen Harry Ltd | Transport & logistics | 2007 |
| Stephen Judd Building and Property Maintenance Limited | Administrative & support | 2008 |
| Stephen Osbiston Limited | Professional & scientific | 2017 |
| Stephenson (MK) Trust | Education | 2012 |
| Stephenson Wass Associates Ltd | Wholesale & retail | 2020 |
| Stepwise Talent Ltd | Administrative & support | 2025 |
| Sterilair UK Ltd | Wholesale & retail | 2019 |
| Sterlia Ltd | Information & communication | 2025 |
| Sterling Accounting & Tax Associates Ltd | Professional & scientific | 2026 |
| Sterling Bio-Security Limited | Administrative & support | 2015 |
| Sterling Business Finance Limited | Financial services | 2024 |
| Sterling Compliance Limited | Administrative & support | 2009 |
| Sterling Cristel Limited | Information & communication | 1992 |
| Sterling Financial Partners Ltd | Professional & scientific | 2026 |
| Sterling Partnership Limited | Financial services | 2003 |
| Sterling Properties Management Ltd | Real estate | 2021 |
| Sterling Solutions HS Ltd | Professional & scientific | 2013 |
| Sterling Steed Ltd | Wholesale & retail | 2024 |
| Sterling Summit Ltd | Wholesale & retail | 2023 |
| Steve Clark Consulting Services Ltd | Professional & scientific | 2019 |
| Steve Joyce GAS Plumbing & Heating Limited | Construction | 2004 |
| Steve Micklewright Contractors Limited | Construction | 2013 |
| Steve Minshull International Limited | Professional & scientific | 2000 |
| Steve Truck & BUS Ltd | Wholesale & retail | 2026 |
| Steve's Autos Ltd | Wholesale & retail | 2026 |
| Steven Elliott Hartley Sipp Limited | Real estate | 2005 |
| Stevenson Pelley Construction Limited | Construction | 2024 |
| Stevie C Design Limited | Wholesale & retail | 2019 |
| Stewart Air Conditioning Limited | Administrative & support | 2020 |
| Stewart Dick Property Services Ltd | Real estate | 2024 |
| Stewart Johnson Partners Limited | Administrative & support | 2026 |
| Stewart Plumbing Limited | Construction | 2018 |
| Stewarts Road Estates Limited | Other services | 2013 |
| STH Plastics Limited | Professional & scientific | 2012 |
| Stick-On-It Limited | Administrative & support | 2018 |
| Still I Rise Therapies Ltd | Health & social care | 2024 |
| Still Waters MK Ltd | Other services | 2025 |
| Stilo Labs Ltd | Information & communication | 2026 |
| Stimulus Personal Training Ltd | Arts & recreation | 2026 |
| Stingray Digital Ltd | Information & communication | 2017 |
| Stir IT UP Limited | Real estate | 2011 |
| Stirling Grey Limited | Professional & scientific | 2011 |
| Stirling People Solutions Ltd | Administrative & support | 2020 |
| Stitch Apothecary Ltd | Wholesale & retail | 2026 |
| Stitch Milton Keynes Ltd | Wholesale & retail | 2016 |
| Stitch&Script Ltd | Manufacturing | 2025 |
| Stitcht Limited | Information & communication | 2017 |
| Stlp Retail Ltd | Wholesale & retail | 2024 |
| STM Aviation Limited | Manufacturing | 2020 |
| Stoaway Filing Systems (UK) Limited | Manufacturing | 2001 |
| Stockbeat Ltd | Other services | 2025 |
| Stockgrove Homes Limited | Construction | 2014 |
| Stockwell Farm Developments Limited | Construction | 2020 |
| Stockwell Lane Management Company Limited | Households | 2022 |
| Stockwood Limited | Financial services | 2019 |
| Stoian’S Design and Build Ltd | Construction | 2025 |
| Stoic Group Limited | Construction | 2021 |
| Stoic Roofing (South) Limited | Construction | 2021 |
| Stoic Shipping Company Ltd | Information & communication | 2019 |
| Stoke Hammond Service Centre Limited | Wholesale & retail | 2007 |
| Stoke Mandeville National Spinal Charity | Health & social care | 2013 |
| Stoke Metal Fabrications Ltd | Manufacturing | 1991 |
| Stokesi Crystal Art Ltd | Arts & recreation | 2024 |
| Stonac Limited | Professional & scientific | 2000 |
| Stone and Granite Holdings Limited | Construction | 2015 |
| Stone Paving Direct Ltd | Construction | 2018 |
| Stone Talent Partners Ltd | Other services | 2023 |