| Seakat Investments Ltd | Real estate | 2019 |
| Seal Construct Ltd | Construction | 2017 |
| Sealey Taverns Ltd | Hospitality | 2026 |
| Sealview Barn Limited | Construction | 2020 |
| Seamless Drylining Ltd | Construction | 2022 |
| Seamless Marketing Ltd | Professional & scientific | 2015 |
| Sean Aldridge Accountancy Limited | Construction | 2006 |
| Sean D Consulting Ltd. | Professional & scientific | 2017 |
| Sean Delaney Therapy Ltd | Health & social care | 2026 |
| Sean Forryan Architecture Ltd | Professional & scientific | 2025 |
| Search People Group Ltd | Administrative & support | 2021 |
| Search Power Ltd | Extraterritorial | 2023 |
| Search Safety Limited | Extraterritorial | 2023 |
| Search Sustainability Ltd | Extraterritorial | 2023 |
| Search Tech Group Limited | Administrative & support | 2018 |
| Search Waste Ltd | Extraterritorial | 2023 |
| Searenity Ltd | Other services | 2021 |
| Seascape Freehold (Highcliffe) Limited | Households | 2018 |
| Seascape Freehold Limited | Households | 2006 |
| Seascape Group Limited | Other services | 2013 |
| Seascape Homes and Property Limited | Real estate | 2016 |
| Seascape South Limited | Construction | 2014 |
| Seashell Property Limited | Real estate | 2019 |
| Seashell Property Management Limited | Hospitality | 2020 |
| Seashells Bournemouth RTM Company Limited | Households | 2025 |
| Seashore Property Limited | Real estate | 2026 |
| Seaside Llandudno Ltd | Hospitality | 2023 |
| Seaside Properties Ltd | Real estate | 2018 |
| Seaside Property Solutions Ltd | Real estate | 2022 |
| Seaside Support Ltd | Health & social care | 2026 |
| Season Crop (UK) Ltd | Agriculture & fishing | 2016 |
| Seasoned Spirits Ltd | Hospitality | 2013 |
| Seasons Dorset Limited | Wholesale & retail | 2020 |
| Seaton Grange Residents Association Limited | Households | 1985 |
| Seaview Technologies Limited | Information & communication | 2018 |
| Seaway Court (Management) Limited | Households | 1972 |
| SEB & GAB Ltd | Extraterritorial | 2011 |
| Sebas Properties Ltd | Real estate | 2025 |
| Sebastian Court Limited | Real estate | 2025 |
| Sebastian James Ltd | Administrative & support | 2016 |
| Sebco Limited | Construction | 2000 |
| Sebek SYK Ltd | Health & social care | 2018 |
| Sebi (UK) Limited | Hospitality | 2004 |
| Seby Transport Ltd | Transport & logistics | 2018 |
| Section 8 Coffee Co. Ltd | Manufacturing | 2019 |
| Secure Life Solutions Ltd | Financial services | 2019 |
| Secured Asset Holdings Limited | Financial services | 2025 |
| Secured Security Systems Limited | Information & communication | 2019 |
| Securit Facilities Ltd | Administrative & support | 2020 |
| Securitytrust Finance Limited | Information & communication | 2018 |
| Seda Services UK Ltd | Manufacturing | 2025 |
| Seda Solutions UK Ltd | Manufacturing | 2025 |
| SEE ME London Limited | Wholesale & retail | 2022 |
| SEE Thru Window Cleaners Limited | Administrative & support | 2009 |
| Seed and Sprout Ltd | Professional & scientific | 2026 |
| Seed Technology Ltd | Education | 2024 |
| SEEDS4BEES Ltd | Wholesale & retail | 2020 |
| Seigen Court Management Limited | Households | 1987 |
| SEL Catering Limited | Hospitality | 2023 |
| Selar Assets Ltd | Real estate | 2025 |
| Select Change Ltd | Education | 2022 |
| Select P.V.C.-U. Trade Systems Limited | Construction | 1993 |
| Select Worldchoice Limited | Administrative & support | 1998 |
| Selenco Group Ltd | Financial services | 2026 |
| Selene Luxury Chocolates Ltd | Manufacturing | 2022 |
| Self Directed Futures Ltd | Health & social care | 2018 |
| Self Project Ltd | Manufacturing | 2022 |
| Self Storage Wimborne Limited | Extraterritorial | 2023 |
| Selin Gurgun Consultancy Ltd | Professional & scientific | 2024 |
| Selina Limited | Real estate | 2002 |
| Sell Advisory Limited | Professional & scientific | 2018 |
| Sell ANY Timeshare Ltd | Real estate | 2021 |
| Sellars & Co.(Bristol)Limited | Real estate | 1947 |
| Selleriq Limited | Information & communication | 2026 |
| Sellpol Ltd | Wholesale & retail | 2022 |
| Selva Heritage LLP | | 2021 |
| SEM Civil Engineering Ltd | Construction | 2016 |
| SEM Vending Ltd | Wholesale & retail | 2020 |
| Semerah Ltd | Hospitality | 2026 |
| Sencitec Limited | Professional & scientific | 2004 |
| SEND4 Ltd | Education | 2022 |
| Sentient Pictures Ltd | Information & communication | 2014 |
| Sentral Heatin and Plummin Servisis Ltd | Other services | 2003 |
| Sentrek Global Security Ltd | Administrative & support | 2025 |
| Sentronics Holdings Limited | Financial services | 2020 |
| Sentronics Limited | Professional & scientific | 2013 |
| Senturion Capital Ltd | Professional & scientific | 2025 |
| Senverico Ltd | Wholesale & retail | 2026 |
| Senza Developments Ltd | Construction | 2018 |
| Septic Tank Experts Ltd | Water & waste | 2019 |
| Sequoia RTM Company Limited | Households | 2004 |
| Serana Properties Limited | Construction | 2011 |
| Serber Ltd | Wholesale & retail | 2023 |
| Serchen Limited | Extraterritorial | 1998 |
| Serelec Ltd | Construction | 2025 |
| Serendipity Legacy Ltd | Financial services | 2025 |
| Serene Solve Limited | Professional & scientific | 2006 |
| Serenity Beach Hotel Ltd | Hospitality | 2024 |
| Serenity Nest Homes Ltd | Health & social care | 2025 |
| Serenity Social Hub Ltd | Health & social care | 2024 |