| SSK Wealth Limited | Financial services | 2015 |
| SSO Events Ltd | Arts & recreation | 2016 |
| SST Building and Development Ltd | Construction | 2019 |
| ST Albans Arts Team CIC | Arts & recreation | 2025 |
| ST Albans BID Limited | Administrative & support | 2017 |
| ST Albans Builders & Roofing Ltd | Construction | 2015 |
| ST Albans Builders Limited | Other services | 2009 |
| ST Albans Car & Van Hire Garage Services & Mot's Ltd | Wholesale & retail | 2019 |
| ST Albans Car and Van Hire Ltd | Extraterritorial | 2010 |
| ST Albans Care Limited | Health & social care | 2018 |
| ST Albans Clinic Limited | Health & social care | 2004 |
| ST Albans Construction Ltd | Construction | 2024 |
| ST Albans Cricket Club Ltd | Arts & recreation | 2022 |
| ST Albans District Chamber of Commerce | Other services | 1999 |
| ST Albans District Citizens Advice Bureau | Health & social care | 1994 |
| ST Albans District Shopmobility | Other services | 2002 |
| ST Albans for Refugees | Health & social care | 2015 |
| ST Albans Glazing Systems Ltd | Construction | 2019 |
| ST Albans Good Neighbour Scheme | Other services | 1998 |
| ST Albans Hearing Ltd | Health & social care | 2023 |
| ST Albans Media Partnership Ltd | Information & communication | 2022 |
| ST Albans Medical Centre Limited | Health & social care | 2011 |
| ST Albans Online Ltd | Hospitality | 2019 |
| ST Albans Plumbing Electrical Ltd | Construction | 2024 |
| ST Albans Plumbing, Boilers & Heating Ltd | Construction | 2019 |
| ST Albans Property Maintenance Ltd. | Construction | 2016 |
| ST Albans Psychology Ltd | Health & social care | 2022 |
| ST Albans Removals Ltd | Transport & logistics | 2025 |
| ST Albans Roleplay and Audio Production Services Ltd | Professional & scientific | 2026 |
| ST Albans Roofing Ltd | Construction | 2020 |
| ST Albans Rooms Ltd | Health & social care | 2022 |
| ST Albans School | Education | 2002 |
| ST Albans School Woollam Trustee Company | Arts & recreation | 2006 |
| ST Albans Seed Tray CIC | Agriculture & fishing | 2025 |
| ST Albans Takeaway Ltd | Hospitality | 2021 |
| ST Albans Taverns Limited | Hospitality | 2011 |
| ST Albans Therapy Ltd | Health & social care | 2026 |
| ST Albans Tiling Limited | Construction | 2014 |
| ST Albans Tree & Garden Services Limited | Administrative & support | 2003 |
| ST Albans Trees Limited | Administrative & support | 2003 |
| ST Albans Trust Limited | Administrative & support | 1915 |
| ST Albans Tutors Limited | Education | 2015 |
| ST Albans Tyres Limited | Wholesale & retail | 2023 |
| ST Albans Upholstery School Limited | Education | 2010 |
| ST Albans Upholstery Studio Ltd | Manufacturing | 2021 |
| ST Albans Van and Car Hire Ltd | Extraterritorial | 2010 |
| ST Albans Van Hire 1 Limited | Extraterritorial | 2010 |
| ST Albans Van Hire Garage Services & Mot's Ltd | Wholesale & retail | 2019 |
| ST Albans Van Hire Ltd | Extraterritorial | 2026 |
| ST Albans Wood Recycling CIC | Water & waste | 2010 |
| ST Apollonia Endo Ltd | Health & social care | 2023 |
| ST Brides Tavern Ltd | Hospitality | 2019 |
| ST Express Logistics Ltd | Transport & logistics | 2016 |
| ST George's Sailing Club CIC | Arts & recreation | 2026 |
| ST Margarets Court RTM Company Limited | Households | 2023 |
| ST Oak Limited | Hospitality | 2020 |
| ST Peters Mews (Central) Ltd | Households | 2025 |
| ST Peters Mews Freehold Company Limited | Real estate | 2014 |
| ST Wenn Scaffolding Ltd | Construction | 1994 |
| ST. Albans and Dacorum Day Hospice | Health & social care | 1991 |
| ST. Albans City Football and Athletic Club Limited | Arts & recreation | 1985 |
| ST. Albans Design and Build Ltd | Construction | 2017 |
| ST. Albans Education Group | Education | 1936 |
| ST. Albans Lawn Tennis Club Limited | Arts & recreation | 1904 |
| ST. Albans M.C. Limited | Households | 1986 |
| ST. Albans Photography Ltd | Professional & scientific | 2014 |
| ST. Georges Court Development Limited | Households | 1990 |
| ST. Lawrence Way Management Limited | Households | 1996 |
| ST. Maryhon Care Services Ltd | Health & social care | 2026 |
| ST. Nicholas Lodge Management Company Limited | Real estate | 1997 |
| STA2TONE Ltd | Professional & scientific | 2026 |
| Staa Solutions Ltd | Other services | 1997 |
| Stableton - Snapn SPV, LLP | | 2022 |
| Stableton 2022 SPV III, LLP | | 2022 |
| Stableton 2022 SPV IV LLP | | 2022 |
| Stableton 2023 SPV I LLP | | 2023 |
| Stableton 2023 SPV II LLP | | 2023 |
| Stableton 2023 SPV III LLP | | 2023 |
| Stableton Financial - Snapn GP, LLP | | 2022 |
| Stableton Financial GP - a, LLP | | 2022 |
| Stableton Financial GP - B, LLP | | 2022 |
| Stackbourne Limited | Construction | 1979 |
| Stage Screen Innovations Ltd | Extraterritorial | 2024 |
| Stagflex Data Limited | Information & communication | 1989 |
| Staid Ltd | Extraterritorial | 2025 |
| Stames Ltd | Professional & scientific | 2025 |
| Stanchion Payment Solutions (UK) Ltd | Information & communication | 2014 |
| Stand Tall Consultancy Ltd | Professional & scientific | 2023 |
| Standard Time Ltd | Extraterritorial | 2025 |
| Standen Mortgages & Life Ltd | Financial services | 2026 |
| Standout Systems Ltd | Manufacturing | 2011 |
| Stanford Europe Limited | Professional & scientific | 2008 |
| Stapleford Skip Hire Ltd | Other services | 2016 |
| Star Events and Partners Ltd | Administrative & support | 2011 |
| Star Prospects Limited | Real estate | 2018 |
| Starfilled Ltd | Real estate | 2025 |
| Starkey Trading Services Ltd | Wholesale & retail | 2024 |
| Starlet Living Limited | Real estate | 2019 |
| Starplex Limited | Administrative & support | 1982 |
| Stashup Ltd | Professional & scientific | 2025 |