| Allmedia Ltd | Information & communication | 2022 |
| Allsparks Electrical Limited | Construction | 2018 |
| Alpha CTI Ltd | Professional & scientific | 2012 |
| Alpha MAY Care First Ltd | Health & social care | 2020 |
| Alpha MAY Project Management Consultants Limited | Professional & scientific | 2010 |
| Alprofil Limited | Manufacturing | 1998 |
| Amazing Lashes Ltd | Wholesale & retail | 2010 |
| Ambrose & Bailey Limited | Information & communication | 2006 |
| Amel Wealth Ltd | Financial services | 2025 |
| Amelia's Hair and Beauty Ltd | Other services | 2011 |
| Amtoc Limited | Professional & scientific | 2024 |
| Anchor Garage Doors Limited | Construction | 2003 |
| Aneta 101 Ltd | Health & social care | 2024 |
| Angel & Anchor Ltd | Professional & scientific | 2021 |
| Angole Ltd | Real estate | 2014 |
| Anil Mistry Ltd | Arts & recreation | 2013 |
| Annton Homes Limited | Real estate | 2022 |
| Another Dimension Brewing Co Ltd | Manufacturing | 2020 |
| Antiquities (Arundel) Limited | Wholesale & retail | 2003 |
| Anwar Property Investments Ltd | Real estate | 2023 |
| Anwcs Ltd | Professional & scientific | 2024 |
| Anxiety Reintegration Mentoring Service (Arms) Limited | Education | 2025 |
| Apex Lofts & Construction Limited | Construction | 2020 |
| Appledown Construction Limited | Construction | 2024 |
| Appleyard Property Limited | Real estate | 2021 |
| Aqua Panda Ltd | Administrative & support | 2024 |
| Aquabeach Yachting Ltd | Manufacturing | 2021 |
| Archevolve (Southern) Limited | Professional & scientific | 2023 |
| Arden Services (West Sussex) Ltd | Real estate | 2017 |
| Argan Capital Advisors LLP | | 2006 |
| Argan Capital B L.P. | | 2006 |
| Argan Capital L.P. | | 2006 |
| Argon Peak Holdings Limited | Financial services | 2023 |
| Aria Peri Capital Limited | Financial services | 2024 |
| Arigant Ltd | Information & communication | 2025 |
| ARP Heating & Plumbing Limited | Construction | 2011 |
| Arthur Lord Organs Ltd | Wholesale & retail | 1972 |
| Asdal Limited | Transport & logistics | 2025 |
| Asgard Residential Ltd | Construction | 2021 |
| Ashlin Investments Ltd | Real estate | 2021 |
| Aston Alexander Ltd | Professional & scientific | 2014 |
| Astra Technologies UK LLP | | 2016 |
| ATO Estates Ltd | Real estate | 2025 |
| Atroporp Ltd | Wholesale & retail | 2020 |
| Audemus Consulting Ltd | Professional & scientific | 2021 |
| Aumento Investments Ltd | Real estate | 2021 |
| Auroral Pictures Limited | Information & communication | 2018 |
| Austen Instant Tapes Limited | Wholesale & retail | 1965 |
| Autocare Collective Ltd | Wholesale & retail | 2020 |
| AV Teknic Ltd | Arts & recreation | 2019 |
| AVA Faltaous Ltd | Transport & logistics | 2025 |
| AVA Minas Ltd | Transport & logistics | 2021 |
| Avalon International Limited | Professional & scientific | 1991 |
| Avalon Systems Ltd | Manufacturing | 2025 |
| Award Investments Limited | Real estate | 2023 |
| AXC Investment Ltd | Financial services | 2019 |
| AXC Solutions Limited | Wholesale & retail | 2013 |
| Axc.Estate Limited | Real estate | 2026 |
| Axis DAS Ltd | Wholesale & retail | 2026 |
| Azilo Investments Limited | Construction | 2025 |
| Azul Coffee and Eatery Ltd | Hospitality | 2023 |
| B & J Morrow Ltd | Wholesale & retail | 2026 |
| B & T Services Limited | Construction | 2003 |
| B J Trade Ltd | Health & social care | 2019 |
| B Stand Ltd | Hospitality | 2025 |
| B.E.S.T Project Homes Ltd | Real estate | 2025 |
| Baikal Clean Ltd | Construction | 2025 |
| Bailey Recovery Limited | Transport & logistics | 2024 |
| Bailey Scaffolding Limited | Construction | 2009 |
| Ballenday Limited | Construction | 2000 |
| BAM BAM Social Limited | Professional & scientific | 2022 |
| Barmic Systems Limited | Professional & scientific | 2000 |
| Bartons Actuarial Services Ltd | Professional & scientific | 2021 |
| Bass Pacific Services Ltd | Extraterritorial | 2016 |
| Bathroom and Fireplace Warehouse Limited | Wholesale & retail | 2022 |
| BAYFORD135 Ltd | Real estate | 2022 |
| BB Investment Property Holdings Ltd | Financial services | 2023 |
| BB Investments Property Limited | Real estate | 2015 |
| BB4 Club Ltd | Arts & recreation | 2025 |
| Beach Breaks Ltd | Real estate | 2022 |
| Beach Green Hotel Limited | Hospitality | 2014 |
| Bear Estate Management Ltd | Construction | 2026 |
| Beazley Sharpe (Railwise) Limited | Professional & scientific | 1998 |
| BEDR0CK Collective Limited | Real estate | 2018 |
| Beje Global Relocation Ltd | Hospitality | 2025 |
| Believe YOU CAN Designs Ltd | Wholesale & retail | 2012 |
| Bella's Art Ltd | Construction | 2024 |
| Belzie Unlimited Ltd | Manufacturing | 2021 |
| BEN Moussa Limited | Health & social care | 2003 |
| BEN Warley Contracting Limited | Professional & scientific | 2018 |
| Benchmark Holdings Group Ltd | Financial services | 2018 |
| Benchmark Projects Limited | Construction | 2018 |
| Benchmark Timber Windows Ltd | Wholesale & retail | 2010 |
| Benchmark Windows Ltd | Wholesale & retail | 2010 |
| Benfield Investments Limited | Arts & recreation | 2004 |
| Berek Group Ltd | Financial services | 2025 |
| Berrys Workshop Ltd | Professional & scientific | 2025 |
| Bespokitch Limited | Wholesale & retail | 2024 |
| Better Hired Ltd | Administrative & support | 2023 |
| Bevec Ltd | Administrative & support | 2018 |