| Sehlik Academic Consultancy Ltd | Professional & scientific | 2023 |
| Seicho Ltd | Wholesale & retail | 2025 |
| SEL Build Limited | Construction | 2019 |
| Sela Care Ltd | Health & social care | 2026 |
| Selago Profecta Development Ltd | Real estate | 2017 |
| Select Abodes Ltd | Real estate | 2025 |
| Select Appointments Ltd | Administrative & support | 2021 |
| Select Planning Ltd | Professional & scientific | 2012 |
| Select Property Refurbishment Limited | Real estate | 2025 |
| Select Recruitment Limited | Administrative & support | 2023 |
| Select Recruitment Specialists Ltd | Administrative & support | 1995 |
| Select Specialist Recruitment Limited | Administrative & support | 2022 |
| Select Star Solutions Limited | Information & communication | 2018 |
| Selective KOI Sales Limited | Wholesale & retail | 1999 |
| Selextar Restaurants Limited | Hospitality | 2002 |
| Self Assured Mind Therapy Ltd | Health & social care | 2023 |
| Self Storage Hire Ltd | Wholesale & retail | 1999 |
| Selfmaid Cleaners Ltd | Administrative & support | 2023 |
| Selkirk Finance Limited | Professional & scientific | 2005 |
| Selltwotravel Ltd | Wholesale & retail | 2021 |
| Selva Retail Ltd | Wholesale & retail | 2021 |
| SEM Management (PTC) Limited | Administrative & support | 2019 |
| Sem-I Health Group Limited | Public administration | 2023 |
| Semblr Technologies Limited | Information & communication | 2018 |
| Semibold Ltd | Information & communication | 2022 |
| Semidice Components Limited | Information & communication | 2012 |
| Semiquip Ltd | Manufacturing | 2016 |
| Semitech-France UK Ltd | Professional & scientific | 2024 |
| Semy Care Ltd | Health & social care | 2021 |
| Sencohaven Ltd | Information & communication | 2026 |
| Send Protect Ltd | Financial services | 2024 |
| Seneye Ltd | Manufacturing | 2010 |
| Seneye Sensors Ltd | Manufacturing | 2025 |
| Senior Care Medical Staffing Ltd | Health & social care | 2025 |
| Senna Mews Management Company Limited | Households | 2020 |
| Sennebec Limited | Other services | 2017 |
| Sense Equine Limited | Wholesale & retail | 2023 |
| Senseseven Ltd | Professional & scientific | 2012 |
| Sensiblysafe Limited | Other services | 2014 |
| SENT2943 Limited | Manufacturing | 2017 |
| Sentinal Industries Ltd | Construction | 2024 |
| Sentinel Asset Finance Ltd | Financial services | 2012 |
| Sentinel Hosting Ltd | Information & communication | 2025 |
| Sentinel Property Ltd | Construction | 2014 |
| Sentinel Property Management Limited | Real estate | 2015 |
| Sentinel Road Limited | Information & communication | 2013 |
| SEO for the Trade Ltd | Professional & scientific | 2026 |
| Seoul Born Ltd | Hospitality | 2023 |
| SEP. 1 Ltd. | Construction | 1997 |
| Sepauto Limited | Wholesale & retail | 2023 |
| Seps Properties Ltd | Real estate | 2019 |
| Septemcore Limited | Information & communication | 2026 |
| Septic Tank Solutions Ltd | Administrative & support | 2020 |
| Sequelisers Ltd | Information & communication | 2020 |
| Sequence Automation Limited | Information & communication | 2014 |
| Sequoia Rise Ltd | Construction | 2022 |
| Serai Tent Ltd | Administrative & support | 2026 |
| Seraview Limited | Real estate | 1983 |
| Serena Care Ltd | Health & social care | 2017 |
| Serendip Private Limited | Health & social care | 2023 |
| Serene Agency Limited | Information & communication | 2021 |
| Serene Safety Limited | Extraterritorial | 2025 |
| Serene Sedation Ltd | Financial services | 2021 |
| Serene Sound Haven Ltd | Arts & recreation | 2024 |
| Serenity Management Ltd | Professional & scientific | 2014 |
| Serenity Property Agents Ltd | Real estate | 2021 |
| Serenitywellness Healthcare Limited | Health & social care | 2023 |
| Serenus Property Limited | Real estate | 2024 |
| Serina Maddock Mortgages Ltd | Financial services | 2021 |
| Serious Software (UK Department) Ltd | Information & communication | 2017 |
| Serotonin Aesthetics Ltd | Other services | 2026 |
| Serpentine Park Limited | Energy | 2013 |
| Serruys Limited | Real estate | 2006 |
| Servant's Church Limited | Other services | 2006 |
| Serve Group Limited | Administrative & support | 2003 |
| Serve Property Limited | Construction | 2021 |
| Serve Recruit Ltd | Professional & scientific | 2021 |
| Serve Talent Limited | Administrative & support | 2006 |
| Service Centre 06 Limited | Professional & scientific | 2004 |
| Service Service Employment Agency Limited | Administrative & support | 1980 |
| Service Trading Group Ltd | Real estate | 2023 |
| Serviced Lettings Group Limited | Real estate | 2018 |
| SES Avocet Limited | Education | 2003 |
| SES Kite Limited | Education | 2020 |
| SES Turnstone Limited | Education | 2012 |
| Sesab Chippy Ltd | Hospitality | 2023 |
| Sesame Trading Ltd | Hospitality | 2011 |
| Sesli Taxis Limited | Manufacturing | 2003 |
| Sesma Martial Arts UK LLP | | 2020 |
| Sesprop Ltd | Real estate | 2025 |
| Sessioncam Limited | Information & communication | 2015 |
| SET Assets Ltd | Real estate | 2023 |
| SET Forth Ltd | Professional & scientific | 2015 |
| Setsquare Energy Solutions Limited | Administrative & support | 2003 |
| Sevco 5123 Limited | Professional & scientific | 2017 |
| Seven East Ltd | Administrative & support | 2019 |
| Seven F.O Ltd | Hospitality | 2020 |
| Seven HILLS70 Ltd | Real estate | 2018 |
| Seven Squared Ltd | Professional & scientific | 2024 |
| Seven Star Products Ltd | Wholesale & retail | 2023 |