| SDM Mechanical Group Ltd | Construction | 2023 |
| SDS Soft Ltd | Information & communication | 2012 |
| Sdsc Quantity Surveying Ltd | Professional & scientific | 2018 |
| Sdshome and Transport Ltd | Transport & logistics | 2026 |
| Sea 2 Sky Construction Ltd. | Construction | 2022 |
| Seagull Properties Limited | Real estate | 2009 |
| Seale Design Ltd | Professional & scientific | 2021 |
| Seamless Solutions Group Ltd | Financial services | 2025 |
| Sean Culey Ltd | Professional & scientific | 2019 |
| Search Answers Limited | Professional & scientific | 1998 |
| Search Solihull Limited | Information & communication | 2018 |
| SEARCHME4 Ltd | Information & communication | 1999 |
| Seasons Coffee House Limited | Wholesale & retail | 2024 |
| Seaspray Shirley Limited | Hospitality | 2018 |
| Seatex Rubber Limited | Manufacturing | 2010 |
| Seaview Holidays Limited | Hospitality | 2009 |
| Seaway Property Investment Ltd | Real estate | 2025 |
| Second City Assets Limited | Wholesale & retail | 2010 |
| Second City Brewery Ltd | Manufacturing | 2022 |
| Second City Payroll Ltd | Administrative & support | 2020 |
| Sectoa (Bham) Ltd | Administrative & support | 2010 |
| Secure Homes Services Limited | Real estate | 1978 |
| Secure Trust Bank Public Limited Company | Financial services | 1954 |
| Secured Supply Ltd | Administrative & support | 2022 |
| Securetech Infrastructure Services Ltd | Professional & scientific | 2025 |
| Security Guards UK Limited | Administrative & support | 2020 |
| Seddon Agency Limited | Administrative & support | 2020 |
| Sedgemere Limited | Professional & scientific | 2013 |
| Seebridge Signs Limited | Manufacturing | 2004 |
| Seeder Ltd | Real estate | 2022 |
| Seeds Child Care Ltd | Education | 2019 |
| Seelo Digital Solutions Limited | Information & communication | 2025 |
| Seethroughwindows Limited | Administrative & support | 2012 |
| Sehmi Enterprises Ltd | Real estate | 2014 |
| Sehmi Real Estate Developments Ltd | Real estate | 2015 |
| Sehra Properties Ltd | Real estate | 2023 |
| Sejand UK Limited | Real estate | 2015 |
| Select a Car Group Ltd | Wholesale & retail | 2021 |
| Select a Car Private Hire Ltd | Transport & logistics | 2024 |
| Select Aesthetics Group Ltd | Wholesale & retail | 2025 |
| Select Wealth Management Limited | Financial services | 2016 |
| Selectgoods Ltd | Wholesale & retail | 2024 |
| Selenium Property Investments LLP | | 2008 |
| Self Care Rituals Ltd | Wholesale & retail | 2021 |
| Selfcare Doctor Ltd | Information & communication | 2020 |
| Selingo Ltd | Professional & scientific | 2024 |
| Sell IT Smoothly Limited | Wholesale & retail | 2022 |
| Sell Your Car 2 Jack Dudley Ltd | Wholesale & retail | 2025 |
| Sell Your Car 2 Jack Leicester Ltd | Wholesale & retail | 2025 |
| Sell Your Car 2 Jack Ltd | Professional & scientific | 2016 |
| Selld Ltd | Other services | 2020 |
| Selsebiel.A Photography Ltd | Other services | 2015 |
| SEM Byrne Ltd | Construction | 2021 |
| Semiara Limited | Professional & scientific | 2023 |
| Semillas Limited | Wholesale & retail | 2018 |
| Semmington Road (Melksham 2) Ltd | Construction | 2023 |
| Semmington Road (Melksham) Limited | Construction | 2022 |
| Senate Property Services Ltd | Real estate | 2019 |
| Senator Power Systems Ltd | Information & communication | 2021 |
| Senclar Properties Ltd | Real estate | 2021 |
| Send Consultancy Ltd | Education | 2019 |
| Sendcloud Limited | Transport & logistics | 2020 |
| Sendit.On Ltd | Transport & logistics | 2024 |
| Senior Care Support Services Ltd | Health & social care | 2012 |
| Senior Response Limited | Other services | 1998 |
| Sensible Planning Ltd | Information & communication | 2013 |
| Senstec Ltd | Professional & scientific | 2024 |
| Sentaa Ltd | Education | 2016 |
| Sentbox Limited | Administrative & support | 2008 |
| Sentinel Fire Safety Limited | Professional & scientific | 2023 |
| Sentryfix Ltd | Information & communication | 2025 |
| Senzone C.I.C. | Health & social care | 2025 |
| Seo.Careers Ltd | Administrative & support | 2024 |
| Sepheneia Ltd | Information & communication | 2025 |
| September Property Limited | Construction | 2017 |
| Serene Care Group Ltd | Health & social care | 2022 |
| Serene N Secure Homes Ltd | Real estate | 2016 |
| Serene Serenity Ltd | Health & social care | 2024 |
| Serene Specialist Care Limited | Health & social care | 2024 |
| Serene Supported Living Ltd | Real estate | 2026 |
| Serenescape Limited | Real estate | 2021 |
| Serengeti Holdings Limited | Real estate | 2019 |
| Serenitas Developments Ltd | Real estate | 2025 |
| Serenitea & Coffee CIC | Hospitality | 2025 |
| Serenity Foster Care Limited | Other services | 2013 |
| Serenity Global Care Limited | Health & social care | 2025 |
| Serenity Specialist Care Limited | Education | 2010 |
| Serenity Specialist Holdings Limited | Financial services | 2021 |
| Serial Marketing Group Ltd | Administrative & support | 2017 |
| Series to Defender Limited | Professional & scientific | 2015 |
| Serious About Print Ltd | Arts & recreation | 2018 |
| Seriously FUN Business Ltd | Administrative & support | 2015 |
| Sero Performance Ltd | Arts & recreation | 2025 |
| Serve LDN Ltd | Manufacturing | 2025 |
| SERVICE764 Ltd | Administrative & support | 2025 |
| Serviceko Ltd | Other services | 2014 |
| Servmed Limited | Health & social care | 2015 |
| Servobuild Limited | Construction | 2022 |
| Servoplan Limited | Construction | 2005 |
| Seven Sparks Property Investments Ltd | Real estate | 2025 |