| Aventido Limited | Other services | 2017 |
| Aves Bidco Limited | Information & communication | 2024 |
| Avianca Group (UK) Limited | Extraterritorial | 2021 |
| Avianca Group International Limited | Financial services | 2021 |
| Avianca Midco 1 Limited | Extraterritorial | 2021 |
| Avianca Midco 2 PLC | Extraterritorial | 2021 |
| Avica Aerospace Ducting Limited | Manufacturing | 2020 |
| Avincis Aviation Management Services Limited | Administrative & support | 2000 |
| Avocado Research Chemicals Limited | Manufacturing | 1992 |
| Avoja Limited | Information & communication | 2023 |
| Avry Leisure Ltd | Hospitality | 2025 |
| Avry Ltd | Arts & recreation | 2022 |
| AW Building Solutions Limited | Construction | 2016 |
| AW Foods Ltd | Hospitality | 2026 |
| AW Marketing Limited | Professional & scientific | 2000 |
| AW Quality and Safeguarding Services Limited | Health & social care | 2018 |
| Awitan Ltd | Real estate | 2018 |
| Awtek Solutions Ltd | Information & communication | 2016 |
| Awtex Ltd | Wholesale & retail | 2021 |
| Axal Golf Ltd | Wholesale & retail | 2022 |
| Axalbion Therapeutics Limited | Manufacturing | 2021 |
| Axia Search Ltd | Administrative & support | 2024 |
| Axias Solutions Limited | Information & communication | 2020 |
| Axis Laminate Fabrication Ltd | Construction | 2020 |
| Axles and Turntables Ltd | Manufacturing | 2016 |
| Axon Moore Group Finance Limited | Financial services | 2024 |
| Axon Moore Group Holdings Limited | Financial services | 2024 |
| Axon Moore Group Ltd | Professional & scientific | 2015 |
| Axon Moore Holdings Limited | Administrative & support | 2021 |
| Axon Vascular Europe Limited | Manufacturing | 2025 |
| Ayada Aesthetics Ltd | Professional & scientific | 2026 |
| Ayazseven Design Ltd | Hospitality | 2020 |
| Aylesbury Automation Limited | Manufacturing | 2000 |
| Aylesford Street Property Management Company Limited | Extraterritorial | 1993 |
| AYN Smile Ltd | Health & social care | 2019 |
| Ayreco Limited | Manufacturing | 2018 |
| AYS Beverages Ltd | Wholesale & retail | 2025 |
| Aystorm Scientific Limited | Administrative & support | 2010 |
| Ayvon Limited | Construction | 2024 |
| AZ Edutech Ltd | Wholesale & retail | 2025 |
| AZ Highway Engineering Limited | Professional & scientific | 2022 |
| Azalea Property Ltd | Real estate | 2021 |
| Azar Estates Limited | Real estate | 2006 |
| Azarbod Medical Ltd | Health & social care | 2018 |
| Azia Associates Ltd | Health & social care | 2021 |
| Azimuth Aviation Limited | Administrative & support | 2014 |
| AZK Services Ltd | Health & social care | 2024 |
| AZS Homes Limited | Real estate | 2026 |
| Azul Investments Ltd | Real estate | 2016 |
| Azurite Infotech Ltd | Information & communication | 2018 |
| B & B Rates Ltd | Professional & scientific | 2021 |
| B & C Energy Solutions Limited | Administrative & support | 2013 |
| B & D Steel Services Limited | Professional & scientific | 1989 |
| B Morrison Dental Ltd | Health & social care | 2022 |
| B P Barnard Limited | Professional & scientific | 2024 |
| B Pratap Limited | Information & communication | 2020 |
| B Smith Packaging (North West) Ltd | Administrative & support | 2025 |
| B W Repair & Maintenance Limited | Professional & scientific | 2012 |
| B&C Investment Management Ltd | Financial services | 2014 |
| B&K Medical Services Ltd | Health & social care | 2016 |
| B&M (NW) Limited | Other services | 2024 |
| B. & D. Steel Limited | Professional & scientific | 1978 |
| B. Beauty Bloom Ltd | Other services | 2025 |
| B. Provenance Ltd. | Manufacturing | 2019 |
| B.A. Select Ltd | Information & communication | 2025 |
| B.C.A. Accountants Limited | Professional & scientific | 2012 |
| B.J.H. Electrical Contractors Limited | Administrative & support | 2001 |
| B.L.S. Insurance Services Limited | Financial services | 2010 |
| B.M.B. Management Services (ST. Annes) Limited | Real estate | 1979 |
| B.S. Pension Fund Trustee Limited | Financial services | 1920 |
| B2 Architecture Ltd | Professional & scientific | 2019 |
| B2B International Marketing Group Limited | Professional & scientific | 2017 |
| B7 ASH Properties Limited | Real estate | 2023 |
| BA Adam Limited | Administrative & support | 2022 |
| BAB Cleaning Services Limited | Administrative & support | 2020 |
| Baboosh Limited | Wholesale & retail | 2020 |
| Baby's Kingdom Ltd | Manufacturing | 2017 |
| Back to the Garden (Bowdon) Limited | Real estate | 2023 |
| Back to the Garden (Lymm) Limited | Education | 2019 |
| Back to the Garden Bowdon (Opco) Limited | Real estate | 2023 |
| Back to the Garden Childcare Limited | Education | 2017 |
| Backdrop Media Ltd | Professional & scientific | 2011 |
| Backhealthy Ltd | Health & social care | 2026 |
| Backtracking Limited | Information & communication | 2026 |
| Badhwar Management Ltd | Real estate | 2023 |
| Badri Consultancy UK Ltd | Financial services | 2024 |
| BAE Hospitality Limited | Administrative & support | 2024 |
| Baerlein Gould Marketing Ltd | Professional & scientific | 2024 |
| Baghdad Gate Constructions Ltd | Construction | 2020 |
| Baguley's of Cheshire Limited | Other services | 2021 |
| Bahawalnagar Limited | Health & social care | 2025 |
| Baiju Kothari Ltd | Health & social care | 2022 |
| Bailey Buckland & Green Limited | Professional & scientific | 2024 |
| Bairstow Eves Limited | Professional & scientific | 1994 |
| Bakaya Properties Ltd | Real estate | 2017 |
| Bake N Shake Limited | Hospitality | 2022 |
| Baker Harris Saunders Group Limited | Professional & scientific | 1986 |
| Baker Hollingworth Associates Limited | Professional & scientific | 1997 |
| Bakerhill Property Holdings (UK) Limited | Real estate | 2022 |
| Balbower Consulting Limited | Administrative & support | 2022 |