| Seamlogic Limited | Manufacturing | 2016 |
| Searchlight Properties Ltd | Real estate | 2018 |
| Seas Pharma Ltd | Wholesale & retail | 2024 |
| Seasons Bradford Ltd | Wholesale & retail | 2024 |
| Seat Hospitality Britain Ltd | Administrative & support | 2021 |
| Seat Hospitality Land Services Limited | Administrative & support | 2024 |
| Seat UK Hospitality Limited | Administrative & support | 2020 |
| Seatfans Events Limited | Wholesale & retail | 2025 |
| Seatpro Events Limited | Wholesale & retail | 2025 |
| Seatpro Limited | Wholesale & retail | 2025 |
| Seattle Investments Ltd | Real estate | 2019 |
| Seazium Ltd | Manufacturing | 2020 |
| Second Huds Solution Ltd. | Professional & scientific | 2019 |
| Secret House of Halo's Limited | Other services | 2023 |
| Secret Owners Club Ltd | Wholesale & retail | 2026 |
| Secrets by Alyaana Ltd | Wholesale & retail | 2022 |
| Secrets by RR Ltd | Other services | 2026 |
| Sector Uniform UK Ltd | Wholesale & retail | 2024 |
| Secure 365 Services Ltd | Administrative & support | 2022 |
| Secure Door Specialist Limited | Construction | 2026 |
| Secure Forth Ltd | Wholesale & retail | 2020 |
| Secure GAS 247 Ltd | Extraterritorial | 2021 |
| Secure Hub Services Ltd | Administrative & support | 2026 |
| Secure Investment Solutions Ltd | Real estate | 2024 |
| Secure Products Limited | Manufacturing | 2013 |
| Secure Risk Solutions Ltd | Financial services | 2014 |
| Secure Sammad Ltd | Transport & logistics | 2022 |
| Secure Sanctuary Ltd | Administrative & support | 2025 |
| Secure Secondary Retention Solutions Limited | Manufacturing | 2019 |
| Secure Straps Solutions Limited | Wholesale & retail | 2026 |
| Secure Tools Limited | Wholesale & retail | 2014 |
| Secure Volt Installations Limited | Construction | 2025 |
| SECURE247 Ltd | Administrative & support | 2026 |
| Secured Homes Doors UK Ltd | Professional & scientific | 2021 |
| Secured Homes Windows and Doors Ltd | Professional & scientific | 2024 |
| Securegate Solution Ltd | Manufacturing | 2025 |
| Securelife Housing Ltd | Real estate | 2026 |
| Securicam Direct Ltd | Wholesale & retail | 2015 |
| Security Contracting Services Ltd | Construction | 2018 |
| Security-Technique Limited | Administrative & support | 2002 |
| Seda Transport Ltd | Transport & logistics | 2023 |
| Sedaro Ltd | Wholesale & retail | 2026 |
| Seedbomb Limited | Administrative & support | 2021 |
| Seeds to SOW Limited | Agriculture & fishing | 2016 |
| Seefeldstrasse Limited | Real estate | 2019 |
| Seefirst Limited | Real estate | 1985 |
| Seen Sheen Limited | Manufacturing | 2025 |
| Sefton Pharma Ltd | Wholesale & retail | 2021 |
| Seis Solutions Ltd | Mining & quarrying | 2010 |
| Sekhon & Sekhon Limited | Real estate | 2017 |
| Selborne Property Developments Limited | Real estate | 2005 |
| Seldom Properties Limited | Real estate | 2003 |
| Select and Drive Ltd | Wholesale & retail | 2026 |
| Select Car Centre Ltd | Wholesale & retail | 2023 |
| Select Cargroup Ltd | Wholesale & retail | 2025 |
| Select Carz Ltd | Wholesale & retail | 2023 |
| Select Court Limited | Households | 2023 |
| Select Tutors Ltd | Education | 2025 |
| Selected Properties Yorkshire Limited | Real estate | 2019 |
| Selective Limited | Extraterritorial | 1939 |
| Selective Print Limited | Extraterritorial | 1975 |
| Selectway Limited | Other services | 2018 |
| Selekt Automotive Limited | Wholesale & retail | 2025 |
| Self Directed Support Services Ltd | Health & social care | 2017 |
| Sellfast Global Ltd | Manufacturing | 2025 |
| Sellmore Group Limited | Real estate | 2021 |
| Seluk Ltd | Households | 2025 |
| Selvyn Anthony Bingham Ltd | Extraterritorial | 2024 |
| Semcam Limited | Manufacturing | 2003 |
| Semjonovs Ltd | Transport & logistics | 2018 |
| Semo Burgers Ltd | Hospitality | 2025 |
| Semper Care and Support Ltd | Health & social care | 2022 |
| Semper Care Ltd | Health & social care | 2019 |
| Semper Porro Limited | Extraterritorial | 2018 |
| Semzz Limited | Financial services | 2024 |
| Send Salaam CIC | Education | 2025 |
| Sender Ltd | Professional & scientific | 2010 |
| Sendo Limited | Transport & logistics | 2025 |
| Senecio Limited | Information & communication | 2017 |
| Sengh Telecoms Ltd | Information & communication | 2024 |
| Senior Electrical & Security Systems Limited | Construction | 2004 |
| Senior Fabrications Limited | Manufacturing | 2002 |
| Sensa Security Ltd | Administrative & support | 2024 |
| Sensation Beds Ltd | Wholesale & retail | 2020 |
| Sensei Sheikh Karate & Kickboxing Academy CIC | Education | 2023 |
| Sensible Outsourcing Ltd | Administrative & support | 2018 |
| Sensorimotor Neurocognitive Therapy Gym Ltd | Professional & scientific | 2024 |
| Sensory Haven WY CIC | Health & social care | 2026 |
| Sensuelle Collection DE Luxe Ltd | Wholesale & retail | 2026 |
| Sentinel Capital Investments Limited | Real estate | 2025 |
| Sentinel Guarding Limited | Administrative & support | 2023 |
| Sentinel Homecare Limited | Health & social care | 2004 |
| Sentiri Ltd | Information & communication | 2025 |
| Sentra Airways Limited | Transport & logistics | 2019 |
| Sentra Group Holdings Limited | Professional & scientific | 2021 |
| Sentra Product Development Ltd | Administrative & support | 2024 |
| Sentristream Ltd | Information & communication | 2019 |
| Sentristream Software Services Ltd | Information & communication | 2025 |
| Sentrix Security Solutions Ltd | Administrative & support | 2026 |
| SEO Aimz Limited | Information & communication | 2024 |