| Amaya Care Homes Limited | Health & social care | 2019 |
| Anastasio Homes Limited | Real estate | 2006 |
| Anastasio Properties LLP | | 2020 |
| AND SEW on Limited | Wholesale & retail | 2006 |
| Andreas DE Jong Ltd | Wholesale & retail | 2022 |
| Animus Limited | Real estate | 1983 |
| Anprop Asset Management Limited | Real estate | 2023 |
| Anthony Property Co. Limited | Financial services | 1990 |
| Antibody Production Services Limited | Other services | 2015 |
| AP Food Creations Ltd | Professional & scientific | 2024 |
| Apex Player Development Ltd | Arts & recreation | 2025 |
| Apolline Ltd | Professional & scientific | 2010 |
| Apple Housing Ltd | Real estate | 2019 |
| Appmattus Limited | Information & communication | 2010 |
| Aptitude Tech DBF Ltd | Real estate | 2019 |
| Aptitude.Ai Limited | Information & communication | 2020 |
| Arcco Props Ltd | Information & communication | 2024 |
| Arctic Developments Ltd | Construction | 2018 |
| Arctic Maintenance Limited | Manufacturing | 2013 |
| Arctic Services Limited | Other services | 1998 |
| Ardman Construction Ltd | Construction | 2023 |
| Area Design Architects Ltd | Professional & scientific | 2024 |
| Arenal Properties Ltd | Real estate | 2018 |
| Aria Media & Sounds Ltd | Wholesale & retail | 2015 |
| Arian Estates Limited | Real estate | 2017 |
| Arjuna Consulting Ltd | Professional & scientific | 2023 |
| Arndev Ltd | Real estate | 2022 |
| Arohana Ventures Limited | Professional & scientific | 2024 |
| Art Nrshinga Limited | Arts & recreation | 2005 |
| Artha Advisory Limited | Professional & scientific | 2023 |
| Arti Care Homes (Gloucester) Limited | Health & social care | 2014 |
| Arti Care Homes (South West) Limited | Health & social care | 2014 |
| Arti Care Homes Limited | Health & social care | 2014 |
| Artistcharm Limited | Construction | 1995 |
| Artscape Group Ltd | Wholesale & retail | 2025 |
| ASA Review Ltd | Professional & scientific | 2012 |
| Asap Property Clearances Ltd | Water & waste | 2020 |
| Asdem Limited | Information & communication | 1988 |
| ASK Prime Security Ltd | Administrative & support | 2025 |
| Aspire Prestige Cars Ltd | Transport & logistics | 2025 |
| AT MED Ltd | Health & social care | 2025 |
| AT Property Services Limited | Real estate | 2024 |
| Atifa Ltd | Transport & logistics | 2021 |
| Attn Limited | Professional & scientific | 2025 |
| Audiocar Equipment Limited | Wholesale & retail | 1979 |
| Authentigirl Ltd | Education | 2026 |
| Auto-Mira Ltd | Wholesale & retail | 2025 |
| AUTO4REPAIRS Ltd | Wholesale & retail | 2023 |
| Autonomic Consulting Services Limited | Information & communication | 2003 |
| Autumn Ellis Ltd | Administrative & support | 2019 |
| Awkward Order Ltd | Manufacturing | 2026 |
| AXO Partners Ltd | Professional & scientific | 2025 |
| BA Accountancy Limited | Professional & scientific | 2016 |
| Babs Luxury Service Ltd | Transport & logistics | 2025 |
| Babymonsters Ltd | Construction | 2012 |
| Badminton Investments Limited | Real estate | 2023 |
| Balanced Financial and Accounting Ltd | Professional & scientific | 2017 |
| Bannermans Dining Ltd | Hospitality | 2016 |
| Barber 1ST Ltd | Other services | 2023 |
| Barn Estate Ltd | Financial services | 2024 |
| Bathrooms and Kitchens Limited | Construction | 2019 |
| Battlers Mews Limited | Real estate | 2014 |
| Baxfield Limited | Professional & scientific | 2020 |
| Beauclair Ltd | Information & communication | 2019 |
| Beaumont Gate Group Ltd | Construction | 2021 |
| Beaumont Gate Management Limited | Households | 1989 |
| Bedford Road Medical Ltd | Real estate | 2024 |
| BEENAIL2 Ltd | Other services | 2024 |
| Beetroot 56 Limited | Administrative & support | 2010 |
| Beeware Limited | Administrative & support | 2000 |
| Befrienders Worldwide | Health & social care | 2012 |
| Believe Sharife Limited | Real estate | 2017 |
| Belle & Pierre Ltd | Information & communication | 2022 |
| Benatti Ltd | Wholesale & retail | 2018 |
| Bengani.Com Ltd | Information & communication | 2009 |
| Benny Lazar Ltd | Information & communication | 2026 |
| Benops Ltd | Information & communication | 2018 |
| Benthic Sciences LLP | | 2002 |
| Bernie's V8'S and Historic Outlaws Ltd | Arts & recreation | 2021 |
| Bespoke AV Ltd | Construction | 2024 |
| Best of Egypt Limited | Administrative & support | 2011 |
| Best of Greece Limited | Administrative & support | 2011 |
| Best Quality Watches Limited | Wholesale & retail | 2009 |
| Bettawood Properties Limited | Real estate | 2018 |
| Bhavesh Kotecha Counselling Ltd | Health & social care | 2010 |
| BHP Architects Limited | Other services | 2010 |
| Bigland Management Limited | Other services | 2008 |
| Bissy Sustainable Energy Limited | Administrative & support | 2026 |
| Bissy's Pretzels Limited | Hospitality | 2015 |
| Bissy's Property Development and Interior Design Limited | Real estate | 2020 |
| Black Wood Marketing Services Limited | Administrative & support | 2024 |
| Blakerig Ltd | Administrative & support | 2025 |
| Blend Media Limited | Administrative & support | 2015 |
| Blenheim Mews Freehold Ltd | Households | 2014 |
| Blocker Limited | Real estate | 2013 |
| Bloom and Co Events Ltd | Arts & recreation | 2025 |
| Blueoak Global Limited | Wholesale & retail | 2023 |
| Bluesky AI Ltd | Other services | 2025 |
| Bluntray (Engineers) Ltd | Manufacturing | 2014 |
| BM Property and Management Ltd | Real estate | 2017 |