| Aurora Tax Services Ltd | Professional & scientific | 2021 |
| Auros Group Limited | Wholesale & retail | 2026 |
| Ausha Limited | Wholesale & retail | 2016 |
| Austin Matley HR & Recruitment Services Ltd | Administrative & support | 2023 |
| Ausys Limited | Information & communication | 2025 |
| Authentic Beauty Ltd | Wholesale & retail | 2019 |
| Auto E Ltd | Manufacturing | 2018 |
| Autochex Limited | Information & communication | 2025 |
| Autodrive Limited | Real estate | 1987 |
| Autogurux Ltd | Wholesale & retail | 2024 |
| Automechanic Limited | Wholesale & retail | 2013 |
| Autumn Events Ltd | Hospitality | 2019 |
| Autumn Systems Ltd | Administrative & support | 2024 |
| Auxa Life Sciences Ltd | Professional & scientific | 2025 |
| AV Charters LLP | | 2023 |
| AV'66 Ltd | Construction | 2017 |
| AVA Concept Audio Video Automation Ltd | Professional & scientific | 2017 |
| Avanti Air Ltd | Construction | 2020 |
| Avenso UK Ltd | Wholesale & retail | 2010 |
| Avenue Elmers Freehold Company Limited | Professional & scientific | 2008 |
| Avenue Elmers Management Company Limited | Households | 1989 |
| Aviacom Limited | Information & communication | 2001 |
| Aviacom World Limited | Professional & scientific | 2013 |
| Aviad Health Insights Ltd | Health & social care | 2022 |
| Avid Marinas Limited | Arts & recreation | 2025 |
| AVL Consultancy Limited | Hospitality | 1986 |
| AVM Technologies Limited | Information & communication | 2022 |
| Avonbold Limited | Professional & scientific | 1999 |
| Avonmor Mews Management Company Limited | Real estate | 2007 |
| Avontade Ltd | Real estate | 2020 |
| Avora Design Apparel Ltd | Wholesale & retail | 2024 |
| Avory Properties Limited | Real estate | 2003 |
| AW Mart Ltd | Wholesale & retail | 2025 |
| AW Painting Limited | Construction | 2019 |
| AW Project Solutions Limited | Professional & scientific | 2016 |
| AW Tiling Services Ltd | Construction | 2024 |
| Awcars Ltd | Wholesale & retail | 2025 |
| Awesome Inventions Limited | Information & communication | 2014 |
| Awesomecorp Limited | Professional & scientific | 2001 |
| Awestem Limited | Education | 2020 |
| AWS Autos Ltd | Wholesale & retail | 2024 |
| AXG Wealth Ltd | Financial services | 2025 |
| AXG WM Ltd | Administrative & support | 2025 |
| Axiom Intelligence Ltd | Information & communication | 2025 |
| AXN Intl Ltd | Information & communication | 2026 |
| AXN Property Services Limited | Construction | 2025 |
| Axure Contract Management Ltd | Financial services | 2025 |
| Ayaansh Properties Limited | Real estate | 2025 |
| Ayazi Ltd | Wholesale & retail | 2023 |
| Aylesbury Waterside Theatre Limited | Arts & recreation | 2000 |
| AYN Ltd | Wholesale & retail | 2022 |
| Ayres Properties Limited | Other services | 2001 |
| Ayvi Solutions Ltd | Professional & scientific | 2025 |
| AYY Engineering Services Ltd | Professional & scientific | 2016 |
| AZ Cars Surrey Ltd | Transport & logistics | 2024 |
| Azaad Limited | Information & communication | 2015 |
| Azalea-Arts Limited | Wholesale & retail | 2022 |
| Azia Advisory Ltd | Wholesale & retail | 2022 |
| Aziz Partners Limited | Information & communication | 2025 |
| Aztec GAS & Construction Ltd | Construction | 2026 |
| Aztech Management Limited | Professional & scientific | 2023 |
| Azure Computers Limited | Administrative & support | 1990 |
| Azure Phoenix Ltd | Information & communication | 2014 |
| AZZ Shops Limited | Wholesale & retail | 2024 |
| B Cert International Ltd | Professional & scientific | 2011 |
| B O C Holdings | Professional & scientific | 1926 |
| B Thackery Developments Ltd | Real estate | 2024 |
| B&G Cleaners Service Ltd | Administrative & support | 2024 |
| B1 Masta Tech Ltd | Manufacturing | 2023 |
| B3LLU Building Ltd | Construction | 2024 |
| B4 Investigate Ltd | Professional & scientific | 2001 |
| B4X Consulting Ltd | Professional & scientific | 2025 |
| BA Securities Limited | Administrative & support | 2019 |
| Babar Retail Ltd | Wholesale & retail | 2025 |
| Babel Developments Ltd | Construction | 2021 |
| Bablock Sports Limited | Wholesale & retail | 1975 |
| Babylon Holdings Limited | Hospitality | 2026 |
| Backbar Limited | Hospitality | 2015 |
| Backbar Pubs Limited | Real estate | 2024 |
| Backflip Oskar Ltd | Wholesale & retail | 2025 |
| BAD Bear Transport Ltd | Administrative & support | 2015 |
| Bagherli Family Holding Company Limited | Financial services | 2026 |
| Bagsport Fabrications Ltd | Manufacturing | 2022 |
| Baigent Carpentry and Construction Ltd | Construction | 2025 |
| Bailey Heritage Estates Ltd | Real estate | 2024 |
| Baileys Jewellery Limited | Wholesale & retail | 2008 |
| Baker Creed Limited | Professional & scientific | 2010 |
| Baker Properties Development Ltd | Construction | 2021 |
| Baker Steel Trading Ltd | Manufacturing | 2014 |
| Bakersgate Courtyard Management Limited | Real estate | 2004 |
| Balance Mechanical and Building Services Ltd | Construction | 2015 |
| Balanced Horse Feeds Limited | Extraterritorial | 1989 |
| Balboasoft Ltd | Information & communication | 2010 |
| Balconie Ltd | Administrative & support | 2015 |
| Baldwin Group Ltd | Wholesale & retail | 2019 |
| Ball & Co Financial Planning Limited | Financial services | 2019 |
| Ballerino Associates Limited | Professional & scientific | 2014 |
| Ballsportz Ltd | Arts & recreation | 2016 |
| Ballysoft Solutions Limited | Information & communication | 2010 |
| Balm Consulting Services Ltd | Professional & scientific | 2022 |