| Ashford Projects Ltd | Construction | 2018 |
| Ashley Howard Consultancy Ltd | Education | 2022 |
| Asla IT Solutions Ltd | Information & communication | 2016 |
| Aspirational Limited | Administrative & support | 2004 |
| ASPIRE2ACHIEVE Limited | Education | 2007 |
| Assurewise Limited | Professional & scientific | 2026 |
| AST Stairlifts Ltd | Wholesale & retail | 2024 |
| AT Home Central Services Ltd | Administrative & support | 2020 |
| Ataberk Turk Atag Ltd | Wholesale & retail | 2024 |
| ATD Systems Ltd | Manufacturing | 2026 |
| Atlasvita Ltd | Wholesale & retail | 2025 |
| Atomcode Ltd | Extraterritorial | 2016 |
| Atota Limited | Information & communication | 2001 |
| Atota Networks Ltd | Information & communication | 2002 |
| Attimore Barn Nursery & Pre-School Ltd | Health & social care | 2022 |
| Attimore Barn Pre-School LLP | | 2009 |
| Attimore Barns Management Company Limited | Real estate | 2007 |
| Atwh Property Ltd | Real estate | 2022 |
| Auberge DU LAC Limited | Hospitality | 2022 |
| August Bratstrom Planet Ltd | Wholesale & retail | 2025 |
| Aura-Ps Ltd | Information & communication | 2018 |
| Aurora Glazing Ltd | Construction | 2021 |
| Aurora Lighting UK Limited | Manufacturing | 2022 |
| Auto Pro Mechanics Ltd | Manufacturing | 2014 |
| Auto Selection Sales Limited | Wholesale & retail | 2019 |
| Auto WIZ Ltd | Wholesale & retail | 2013 |
| Autobody REPAIR1 Ltd | Wholesale & retail | 2023 |
| Autoresq Limited | Wholesale & retail | 2026 |
| Autosync Ltd | Information & communication | 2021 |
| Avari Limited | Professional & scientific | 2000 |
| AVD365 Limited | Information & communication | 2023 |
| Avnolu Limited | Health & social care | 2022 |
| Avon Tree Care Limited | Administrative & support | 2018 |
| AW Nexus Limited | Wholesale & retail | 2023 |
| Axalta Coating Systems U.K. (2) Limited | Financial services | 2013 |
| Axalta Coating Systems U.K. (3) Limited | Financial services | 2023 |
| Axalta Coating Systems UK Holding Limited | Financial services | 2012 |
| Axalta Coating Systems UK Limited | Manufacturing | 1988 |
| Axalta Powder Coating Systems UK Limited | Manufacturing | 1972 |
| Ayinla Group Ltd | Wholesale & retail | 2019 |
| Aylott Enterprises Limited | Real estate | 2020 |
| Azaz Construction Limited | Construction | 2025 |
| Azur Pinede Limited | Professional & scientific | 2022 |
| B C G (Holdings) Limited | Other services | 1992 |
| B G Sweeney Ltd | Construction | 2009 |
| B K Car Rentals Limited | Administrative & support | 2014 |
| B N Dhokia Ltd | Health & social care | 2019 |
| B&B Autos Ltd | Wholesale & retail | 2020 |
| B&Bpropertiesuk Limited | Real estate | 2024 |
| B-Hive Properties Ltd | Real estate | 2014 |
| B-Safe Security Group Ltd | Administrative & support | 2019 |
| B.L. Autos & Sons Limited | Wholesale & retail | 2001 |
| B.O.B. Realisations Limited | Manufacturing | 1985 |
| Babsalam Umra & Hajj Agency Limited | Administrative & support | 2002 |
| Baby Swimming Hertfordshire LLP | | 2015 |
| Bacb Properties Limited | Real estate | 2024 |
| Back Office Ventures Limited | Financial services | 2026 |
| Bahu Ltd | Information & communication | 2016 |
| Bajaj Enterprises Ltd | Wholesale & retail | 2018 |
| Baksa Limited | Construction | 2011 |
| Balance for Teachers Ltd | Public administration | 2021 |
| Ball IQ Ltd | Professional & scientific | 2026 |
| Baohan Ltd | Other services | 2024 |
| Bare Knuckle Boxing Magazine Ltd | Manufacturing | 2018 |
| Barleycroft Limited | Construction | 1985 |
| Barn Theatre Club Limited | Arts & recreation | 1963 |
| Barn Theatre Trust Limited(The) | Arts & recreation | 1981 |
| Barros Family Care Ltd | Health & social care | 2025 |
| Battbun Services Limited | Information & communication | 2018 |
| Baturalp Uzuner Ltd | Wholesale & retail | 2024 |
| BB Electro Company Limited | Construction | 2022 |
| Bbav Investments Ltd | Real estate | 2024 |
| BBB M&E Services Limited | Construction | 2023 |
| BBM Cleaners Ltd | Administrative & support | 2025 |
| BCG Market Research Services Ltd | Other services | 1992 |
| BDL Consultancy Ltd | Professional & scientific | 2025 |
| BE Elegant Ltd | Wholesale & retail | 2025 |
| Beacon Digital Media Limited | Information & communication | 2014 |
| Bearstone Properties Limited | Real estate | 2022 |
| Bearstone Software Limited | Information & communication | 2025 |
| Becca LEE Coaching Ltd | Education | 2025 |
| BEE Morti UK Limited | Hospitality | 2014 |
| Beechwood Financial Services (Holdings) Limited | Financial services | 2015 |
| Beechwood Financial Services Limited | Financial services | 2015 |
| Beehive Holdings Ltd | Real estate | 2016 |
| Beehive Lock & Security Ltd | Other services | 2025 |
| Beekind Honey and WAX Ltd | Agriculture & fishing | 2023 |
| Bees & Cees Limited | Health & social care | 2015 |
| Belgravia Pharma Ltd | Wholesale & retail | 2023 |
| Bell and Sons Ecotech Ltd | Construction | 2022 |
| Bell Mews Freehold Limited | Households | 2023 |
| Bellch Limited | Wholesale & retail | 2023 |
| Bellcrown Consultancy Limited | Professional & scientific | 2010 |
| Belle and RAE Limited | Households | 2024 |
| Bensonsapartments Ltd | Hospitality | 2025 |
| BEQ Services Ltd | Administrative & support | 2025 |
| Bescom Ltd | Wholesale & retail | 2024 |
| Bessemer Road Management Company Limited | Real estate | 2001 |
| Best Biryanis Ltd | Hospitality | 2025 |
| Bestway Car Ltd | Wholesale & retail | 2022 |