| Atlas Carre Ltd | Manufacturing | 2023 |
| Atlas Health Capital Advisers LLP | | 2025 |
| Atlas Health Capital Ltd | Professional & scientific | 2026 |
| Atlas Transport & Logistics Ltd | Transport & logistics | 2020 |
| Atoshi Ltd | Professional & scientific | 2017 |
| Attogroup Ltd | Wholesale & retail | 2020 |
| Attraction Tickets Ltd | Administrative & support | 2002 |
| Attune Therapeutics Ltd | Health & social care | 2026 |
| Audentes Leisure Ltd | Hospitality | 2019 |
| Audhd Forward Ltd | Other services | 2024 |
| Audio Design Inspiration Limited | Information & communication | 2013 |
| Audiocreate Limited | Wholesale & retail | 2001 |
| Audiofreaks Limited | Wholesale & retail | 1997 |
| Audiosigns Ltd | Manufacturing | 2015 |
| Audouin Wright Consulting Ltd | Professional & scientific | 2025 |
| Auer Design Services Limited | Administrative & support | 2007 |
| August Bakery Ltd | Manufacturing | 2024 |
| Augusta Capital Management Limited | Other services | 2023 |
| Auracor Ltd | Real estate | 2019 |
| Aurelius Advisers Limited | Professional & scientific | 2014 |
| Aurella Ltd | Information & communication | 2025 |
| Auren Group Ltd | Construction | 2025 |
| Aurora Metro Arts and Media Ltd. | Information & communication | 1996 |
| Aurora Metro Publications Ltd | Information & communication | 1988 |
| Aurum Estate Holdings Limited | Real estate | 2020 |
| Aurum International Education Limited | Education | 2025 |
| Ausbrough Limited | Professional & scientific | 2020 |
| Auspice Corner Ltd | Hospitality | 2025 |
| Austeya Creative Group Ltd | Agriculture & fishing | 2026 |
| Australian Sky Limited | Professional & scientific | 2006 |
| Avantgarde Advisory Limited | Professional & scientific | 2010 |
| Avask Global Compliance Ltd | Information & communication | 2012 |
| AVI Mack Productions Limited | Information & communication | 2024 |
| Aviation International Limited | Information & communication | 2021 |
| Avid Architects Ltd | Professional & scientific | 2020 |
| Avidus Consulting Limited | Information & communication | 2005 |
| AW Sales AI Limited | Information & communication | 2023 |
| AWF Medical Ltd | Health & social care | 2013 |
| AWI Services Limited | Information & communication | 2020 |
| Awsm Farming Limited | Agriculture & fishing | 2011 |
| Awsm Recycling Limited | Water & waste | 2007 |
| Awsm Storage Solutions Ltd | Agriculture & fishing | 2021 |
| Awte UK Limited | Other services | 2005 |
| Axcillium Ltd | Information & communication | 2022 |
| Axiom Connected Ltd | Information & communication | 2020 |
| Axisk Ltd | Wholesale & retail | 2026 |
| Axplore Travel Ltd | Administrative & support | 2019 |
| Aydan Properties Limited | Real estate | 2011 |
| Ayesgarth Consultants Limited | Professional & scientific | 2013 |
| Ayooda.Com Ltd | Information & communication | 2006 |
| Azahara Tarsis Group Ltd | Professional & scientific | 2025 |
| Azcf Ltd | Real estate | 2017 |
| Azekor Limited | Administrative & support | 2015 |
| Aziairtech Ltd | Manufacturing | 2026 |
| Azure Trading Partners Limited | Wholesale & retail | 2024 |
| B & T Kitson Limited | Wholesale & retail | 2002 |
| B a Partnership Ltd | Real estate | 2018 |
| B Bowser Limited | Households | 2025 |
| B C Information Limited | Information & communication | 2011 |
| B P Garage Services Limited | Wholesale & retail | 1997 |
| B&B Ndreu Construction Ltd | Construction | 2022 |
| B&R Couriers Ltd | Administrative & support | 2017 |
| B-Cam Ltd | Wholesale & retail | 2012 |
| B-Features Limited | Arts & recreation | 2022 |
| B-Hive Block Management Partners Limited | Households | 1989 |
| B-Hive Property Solutions Limited | Extraterritorial | 2017 |
| B-Hive Site Staff Solutions Limited | Administrative & support | 2004 |
| Babers of Blackwood Limited | Real estate | 1953 |
| BAC Construction Services Limited | Water & waste | 2015 |
| Bacchus & Co. Ltd | Hospitality | 2025 |
| Bacco Restaurant Limited | Hospitality | 2015 |
| Backbone Productions Limited | Information & communication | 2020 |
| BAD Sector Ltd | Information & communication | 2025 |
| Badem Consultancy Ltd | Real estate | 2017 |
| Bahariblu Limited | Professional & scientific | 2024 |
| Baillea's Interiors Ltd | Wholesale & retail | 2020 |
| Bainbridge Farming Ltd | Agriculture & fishing | 2025 |
| Baker Baker (Developments) Limited | Real estate | 1982 |
| Balder Logistikk Ltd | Wholesale & retail | 2021 |
| Baleal Ltd | Information & communication | 2026 |
| Ballardie Associates Ltd | Financial services | 2015 |
| Baltic Travel (Tour Operator) Limited | Administrative & support | 2004 |
| Bam-Birdie Limited | Wholesale & retail | 2022 |
| Bamboo Bubble Ltd | Professional & scientific | 2023 |
| Bandai Namco Amusement Europe Limited | Arts & recreation | 1993 |
| Bandai Namco Entertainment UK Ltd. | Information & communication | 1987 |
| Bandai Namco Holdings UK Limited | Wholesale & retail | 1991 |
| Bandera Capital Management Ltd | Information & communication | 2022 |
| Bantam Materials UK Limited | Wholesale & retail | 2011 |
| Barbarella Limited | Other services | 2025 |
| Barbersmiths Richmond Limited | Other services | 2025 |
| Bardoni Properties Ltd | Real estate | 2022 |
| Bark Social Ltd | Professional & scientific | 2020 |
| Barker Chickens Limited | Agriculture & fishing | 2009 |
| Barkers of Richmond Limited | Hospitality | 2003 |
| Barkers Restaurant Limited | Hospitality | 2019 |
| Barn Education Association Limited (the) | Education | 1967 |
| Barnard Castle Aviation Limited | Transport & logistics | 2017 |
| Barningham Estate Farms Limited | Agriculture & fishing | 2014 |
| Barrenjoey Capital Ltd | Financial services | 2007 |