| Sdcs Building Maintenance Ltd | Construction | 2025 |
| Sdcs Contracts Ltd | Construction | 2025 |
| Sdcs Holdings Ltd | Real estate | 2026 |
| SDK3 Ltd | Wholesale & retail | 2019 |
| SDM Fabrication Limited | Construction | 2011 |
| SDN Consulting Limited | Professional & scientific | 2018 |
| SDW Tax Consultancy Ltd | Professional & scientific | 2016 |
| SE Installations Limited | Wholesale & retail | 1998 |
| Sea & Land Power and Energy Limited | Professional & scientific | 2010 |
| Sea and Land Project Holdings Limited | Financial services | 2020 |
| Sea and Land Projects Limited | Manufacturing | 2009 |
| Sea and Land Solutions Ltd | Professional & scientific | 2022 |
| Sea Frost Ltd | Wholesale & retail | 2020 |
| Sea Mews Management Co Limited | Households | 2013 |
| Sea Palling Cycle Hire Ltd | Arts & recreation | 2010 |
| Sea Palling Independent Lifeboat Limited | Health & social care | 1974 |
| Sea View Cafe Ltd | Hospitality | 2016 |
| Seafloor Mapping Limited | Professional & scientific | 2002 |
| Seaglaze Group Limited | Financial services | 2014 |
| Seaglaze Ltd | Manufacturing | 1996 |
| Seaglaze Marine Windows Limited | Manufacturing | 1970 |
| Sealcourt Limited | Professional & scientific | 1987 |
| Sealey & Co Properties Ltd | Real estate | 2023 |
| Seals Hospitality Limited | Hospitality | 2018 |
| Sean Alexander Productions Ltd | Arts & recreation | 2017 |
| Sean and Co. Enterprises Limited | Extraterritorial | 2000 |
| Search Design Ltd | Professional & scientific | 2022 |
| Search Engine Marketing Specialists Limited | Information & communication | 2010 |
| Search Forward Limited | Professional & scientific | 2014 |
| Search ME Marketing Limited | Professional & scientific | 2024 |
| Search Peak Limited | Extraterritorial | 2014 |
| Searchair Limited | Real estate | 1999 |
| Searchvis Ltd | Information & communication | 2021 |
| Seareach Diving Consultancy (SCD) Ltd | Other services | 2019 |
| Sears & Bacon Construction Limited | Construction | 2017 |
| Seaside Photography Limited | Professional & scientific | 2012 |
| Seasonal Enterprise Ltd | Wholesale & retail | 2010 |
| Seaview Court Owners Association Limited | Households | 2007 |
| Seaview Granite and Marble Limited | Wholesale & retail | 2016 |
| Seaward Safety Limited | Manufacturing | 1994 |
| Seawood Management Company Limited | Real estate | 2020 |
| SEB Insulation Limited | Construction | 2015 |
| Sebaco Limited | Real estate | 2023 |
| Sebald Limited | Arts & recreation | 1997 |
| Sebastien Mesnage Ltd | Information & communication | 2018 |
| Sebton Civil Engineering Limited | Construction | 2023 |
| SEC Romford Ltd | Real estate | 2018 |
| Secco Group Ltd | Professional & scientific | 2019 |
| Secker Construction Ltd | Construction | 2018 |
| Seckler Consulting Limited | Information & communication | 2023 |
| Secomms Limited | Professional & scientific | 2016 |
| Second Bite Community Interest Company | Wholesale & retail | 2020 |
| Second City Autosales Ltd | Administrative & support | 2015 |
| Second Shot Coffee CIC | Hospitality | 2015 |
| Secondbridge Holdings Limited | Professional & scientific | 2007 |
| Secret Getaways in Norfolk Ltd | Real estate | 2018 |
| Secret Ingredient Music & Events Limited | Arts & recreation | 2018 |
| Secret Radar Ltd | Information & communication | 2025 |
| Securatan Group Limited | Financial services | 2025 |
| Secure & Protect UK Ltd | Administrative & support | 2025 |
| Secure by Integrity Limited | Administrative & support | 2012 |
| Secure Defence UK Limited | Administrative & support | 2012 |
| Secure Edge Protection Ltd | Administrative & support | 2025 |
| Secure Homes Security Limited | Administrative & support | 2017 |
| Secure I.T. Networks Limited | Information & communication | 2005 |
| Secure Investment Group Limited | Hospitality | 2018 |
| Secure Medics Limited | Extraterritorial | 2014 |
| Secure Plus (Cctv) Ltd | Administrative & support | 2003 |
| Secure Stratum Limited | Information & communication | 2024 |
| SECURE3 Services Ltd | Construction | 2024 |
| SECURE3 Systems Ltd | Administrative & support | 2011 |
| Secured Lending Limited | Energy | 2014 |
| Securicom Services Limited | Administrative & support | 2005 |
| Securicomms Limited | Construction | 2012 |
| Securilec UK Limited | Construction | 2006 |
| Security 365 Ltd | Administrative & support | 2016 |
| Security 4 the North Ltd | Administrative & support | 2024 |
| Security and Training Services Limited | Administrative & support | 2011 |
| Security Circuit Limited | Professional & scientific | 2023 |
| Security Solutions YES Limited | Construction | 2006 |
| Secutec International Ltd | Professional & scientific | 2016 |
| Seddy Beauty Studios Ltd | Other services | 2023 |
| Seddy Initiative CIC | Administrative & support | 2026 |
| Sedno Consulting Ltd | Professional & scientific | 2018 |
| Seed Architecture and Planning Limited | Professional & scientific | 2025 |
| Seed Consulting International Limited | Professional & scientific | 2018 |
| Seed Marketing International Ltd | Administrative & support | 2016 |
| Seeding Hope CIC | Agriculture & fishing | 2021 |
| Seeker Financial Planning Limited | Financial services | 2020 |
| Seeker Specialist Mortgages Limited | Financial services | 2024 |
| Seeky Ltd | Information & communication | 2026 |
| Seen Digital Ltd | Professional & scientific | 2009 |
| Seen Interiors Limited | Professional & scientific | 2007 |
| Seepaul (UK) Ltd | Health & social care | 2010 |
| Seeswell Limited | Information & communication | 2012 |
| Sefton Data Centres Limited | Real estate | 2026 |
| Segetta Limited | Information & communication | 2026 |
| Seguro Group Services Ltd | Real estate | 2026 |
| Sehgal News Ltd | Wholesale & retail | 2014 |
| Sehjals Desserts Ltd | Hospitality | 2020 |