| Albany Scaffolding Limited | Construction | 2010 |
| Albatross Heating Ltd | Construction | 2016 |
| Albion Boxing Club Limited | Education | 2022 |
| Alconleigh Supply Ltd | Arts & recreation | 2025 |
| Alderney Air Ambulance Limited | Transport & logistics | 2019 |
| Alexander Associates Technical Recruitment Ltd | Administrative & support | 1996 |
| ALL About Security Ltd | Construction | 2018 |
| ALL in Skin Ltd | Other services | 2024 |
| ALL Junk Collections Ltd | Water & waste | 2022 |
| ALL Seasons Roofing and Construction Ltd | Construction | 2025 |
| Allduct Equipment Supplies Ltd | Wholesale & retail | 2018 |
| Allseasons PAW Park Ltd | Agriculture & fishing | 2024 |
| Allsorts Design & Print Limited | Manufacturing | 2006 |
| Alternative Wedding Fayre Ltd | Administrative & support | 2025 |
| Amadeus Acquisitions Ltd | Real estate | 2025 |
| Amdon(Electrical)Limited | Construction | 1964 |
| AMG Consortium Ltd | Construction | 2014 |
| Amree Ltd | Real estate | 2022 |
| Ams(Au) Ltd | Real estate | 2019 |
| Ancelec Limited | Construction | 2016 |
| Anchor Construction Logistics Limited | Construction | 2013 |
| Anchor Personnel Limited | Administrative & support | 2017 |
| Anderson Lowe Limited | Construction | 2001 |
| Angels & Roses Limited | Hospitality | 2024 |
| Annihilated Wasps Limited | Professional & scientific | 1994 |
| Aofb Telecom Networks Limited | Information & communication | 2017 |
| AOR Services Limited | Construction | 2016 |
| Aotea Associates Limited | Professional & scientific | 2009 |
| Apex Hunt Ltd | Administrative & support | 2024 |
| APH Electrical Limited | Energy | 2015 |
| Aplin & Co Chauffeurs Ltd | Transport & logistics | 2013 |
| Apollo Futures Ltd | Administrative & support | 2026 |
| Applied Consultancy Ltd | Other services | 2025 |
| Approved Cars Limited | Wholesale & retail | 2012 |
| Aptus Consulting Ltd | Professional & scientific | 2020 |
| Aqualisa Holdings (International) Limited | Financial services | 2015 |
| Aqualisa Holdings Limited | Financial services | 2012 |
| Ardenmere Construction Ltd | Construction | 2021 |
| Arigy Transport Ltd | Transport & logistics | 2023 |
| Aris United Limited | Real estate | 2019 |
| ARK NOX Limited | Education | 2025 |
| Arlinda Ltd | Information & communication | 2017 |
| Arlon Interactive Marketing Limited | Professional & scientific | 2004 |
| ARO Affinity Limited | Extraterritorial | 2011 |
| ARO Online Limited | Extraterritorial | 2013 |
| ARO Risk Limited | Extraterritorial | 2011 |
| ARO Underwriting Group Limited | Financial services | 2011 |
| Arpn Property Services Limited | Construction | 2022 |
| Artristic UK Ltd | Other services | 2016 |
| AS Landscaping Ltd | Administrative & support | 2025 |
| Ascot Place Limited | Real estate | 1994 |
| Asec Electrical Ltd | Construction | 2022 |
| ASH Landscape Maintenance Limited | Other services | 2008 |
| Ashbury Tiles Limited | Construction | 2000 |
| Ashillassociates Ltd | Information & communication | 2018 |
| Asprey Homes Limited | Construction | 1995 |
| Asprey Homes Southern Limited | Real estate | 2008 |
| Assured Water Hygiene Limited | Professional & scientific | 2017 |
| Astonishing Luxury Events Limited | Arts & recreation | 2025 |
| ASW Heating Limited | Professional & scientific | 2021 |
| AT Eco Windows & Doors Limited | Construction | 2014 |
| ATG Biohazard Cleaning Limited | Administrative & support | 2025 |
| Athena Fmcg Ltd | Professional & scientific | 2024 |
| Attard Consultancy Limited | Construction | 2023 |
| Attridge Associates Ltd | Professional & scientific | 2018 |
| Aura X Aesthetics Ltd | Other services | 2025 |
| Aurus Nest Services Ltd | Administrative & support | 2026 |
| Auto Electrical Installations Limited | Construction | 2004 |
| Autobody Craft UK Limited | Wholesale & retail | 2004 |
| Autoparts Recycling (UK) Ltd | Wholesale & retail | 2024 |
| AVA Support Network Limited | Administrative & support | 2022 |
| Avalon Aero Technical Publications Ltd | Transport & logistics | 2023 |
| Avalon Aero Technical Services Limited | Transport & logistics | 2009 |
| Avant Accounting Solutions Limited | Professional & scientific | 2018 |
| Aventi AV Limited | Construction | 2021 |
| Aviation Asset Management Limited | Manufacturing | 2016 |
| AW Plumbing Heating Ltd | Construction | 2026 |
| Awake Studios Limited | Information & communication | 2026 |
| AXIS360 Ltd | Professional & scientific | 2019 |
| Azada Consultancy LLP | | 2012 |
| B & Z Developments Limited | Wholesale & retail | 2003 |
| B Bridges Ltd | Manufacturing | 2023 |
| B Manning Heating & Plumbing Services Ltd | Construction | 2014 |
| B&D Contractors Limited | Construction | 2013 |
| Baarc Ltd | Professional & scientific | 2017 |
| Babycham Productions Limited | Information & communication | 2017 |
| Badger Bathrooms Limited | Construction | 2003 |
| Bailey Bodyshop Ltd | Wholesale & retail | 2017 |
| Bailey Country Estates Ltd | Real estate | 2025 |
| Bakery by Charlotte Limited | Manufacturing | 2020 |
| Ball Automotive Ltd | Wholesale & retail | 2015 |
| Balmont Ltd | Construction | 2013 |
| Baltic Amber London Limited | Construction | 2012 |
| Barrow Heath Shooting Ground Ltd | Arts & recreation | 2013 |
| Bartol Banks Technologies Limited | Professional & scientific | 2014 |
| Barzan Westerham Barber Ltd | Other services | 2024 |
| Base Roofing Specialists Ltd | Construction | 2011 |
| Bassetts (Tatsfield) Management Limited | Households | 2013 |
| Baulf International Limited | Administrative & support | 2011 |
| Bay Trees Management Company Limited | Real estate | 2006 |