| Andmore IT Limited | Information & communication | 2017 |
| Andre Noir Limited | Wholesale & retail | 1984 |
| Andrew Cooper Cpec Limited | Professional & scientific | 2008 |
| Andrew Crook Metalsmiths Limited | Manufacturing | 2011 |
| Andrew Donaldson Services Limited | Administrative & support | 2016 |
| Andrew Lodge Limited | Real estate | 2002 |
| Anerley Windows Limited | Construction | 2014 |
| Anexys Communications Limited | Information & communication | 2007 |
| Angel Mountain Developments Ltd | Construction | 2023 |
| Angel Technology Limited | Manufacturing | 2001 |
| Angela Best Limited | Wholesale & retail | 2011 |
| Angela Weller Limited | Administrative & support | 2015 |
| Angie PA Ltd | Administrative & support | 2016 |
| Anglican Church Trustees (Egypt) Limited(The) | Extraterritorial | 1937 |
| Anglo-Asian Associates Limited | Education | 1994 |
| Anima Advocacy Ltd | Education | 2019 |
| Anjeli Investments Limited | Financial services | 2016 |
| Anna Grace Studio Limited | Professional & scientific | 2022 |
| Anna Murtaza Global Limited | Administrative & support | 2025 |
| Annie's Nannies Ltd | Administrative & support | 2021 |
| ANS Fidum Ltd | Information & communication | 2018 |
| ANS Property Investments Limited | Real estate | 2014 |
| Ansador Holdings Limited | Professional & scientific | 2001 |
| Anscombe and Sons Limited | Construction | 2013 |
| Anstey & Stone Ltd | Construction | 2016 |
| Anthea's PR Workshop Ltd | Administrative & support | 2014 |
| Anthem Public Relations Limited | Administrative & support | 2021 |
| Antonia LIU Ltd | Professional & scientific | 2025 |
| Antonio Gonzalez DE Haro Ltd | Transport & logistics | 2018 |
| Anvil Coffee Limited | Manufacturing | 2017 |
| Aoraki Advisory Limited | Information & communication | 2018 |
| AP Consults Ltd | Professional & scientific | 2025 |
| Apache Media Limited | Information & communication | 2007 |
| Apartment Stream Limited | Administrative & support | 2015 |
| Apex Masonry Contractors Limited | Construction | 1999 |
| Apparance Industries Limited | Information & communication | 2018 |
| Apparance Limited | Information & communication | 2018 |
| Apparance Studios Limited | Information & communication | 2018 |
| Appelbridge Limited | Mining & quarrying | 2017 |
| Appetite 4 Hospitality Ltd | Financial services | 2023 |
| Apple Environmental Limited | Professional & scientific | 2002 |
| Appledoor Property Limited | Real estate | 2025 |
| Applied Intelligence and Innovation Ltd | Professional & scientific | 2025 |
| Applied IPR Ltd | Professional & scientific | 2014 |
| Appurity Connect Limited | Information & communication | 2014 |
| Appurity Limited | Information & communication | 2011 |
| April Skies Accounting Limited | Professional & scientific | 2022 |
| Aqetas Limited | Professional & scientific | 2015 |
| Aqua Design Plumbing & Heating Limited | Construction | 2011 |
| Aquae Sulis Student Lets Limited | Real estate | 2021 |
| Aquarius Close (Crondall) Residents Management Company Limited | Households | 2005 |
| Aquila International Consulting Ltd | Professional & scientific | 2020 |
| Aquinna Mews (Addlestone) Management Company Limited | Households | 2013 |
| AR Innovations Ltd | Information & communication | 2025 |
| Arbiter Bespoke Limited | Manufacturing | 2016 |
| Arbor Heights (Management) Limited | Households | 2004 |
| Arborfield Close Residents (Sixteen) Limited | Households | 1976 |
| Arbsystem Ltd | Agriculture & fishing | 2017 |
| ARC Energy Consulting Limited | Professional & scientific | 2023 |
| ARC Payments Limited | Information & communication | 2025 |
| Arcademy Design Limited | Professional & scientific | 2010 |
| Arch Scaffolding Ltd | Construction | 2019 |
| Archenfield Consulting Limited | Professional & scientific | 2011 |
| Archer Ventures Limited | Professional & scientific | 2012 |
| Archetypal Design Ltd | Other services | 2013 |
| Architecture Music Group Ltd | Information & communication | 2024 |
| Arcturus PVT Ltd | Information & communication | 2023 |
| Ardent Automotive Ltd | Wholesale & retail | 2020 |
| Ardlands Co Ltd | Real estate | 2019 |
| Ardnas Eigrah Ltd. | Real estate | 2013 |
| Ardwick Limited | Real estate | 2006 |
| Argo Navis Ltd | Professional & scientific | 2018 |
| Argyle Metals Limited | Manufacturing | 1978 |
| Argyll Lodge Management Company Limited | Households | 2006 |
| ARH Water Treatment Limited | Water & waste | 2018 |
| Aria Advisory Limited | Administrative & support | 2018 |
| Arizia Ltd | Other services | 2023 |
| ARK Management Company (Farnham) Limited(The) | Hospitality | 1985 |
| Arkell Park Management Company Limited | Households | 2025 |
| Arkhos Limited | Financial services | 2019 |
| Arktis Radiation Detectors UK Limited | Manufacturing | 2017 |
| ARM Fibrous Plaster Mouldings Limited | Manufacturing | 2013 |
| Armorel London Limited | Real estate | 2015 |
| Armstrong Removals Fleet Ltd | Transport & logistics | 2024 |
| Arnold & SON (Petersfield) Limited | Wholesale & retail | 2012 |
| ARQ Advisors Limited | Other services | 2024 |
| Arrowood Communications Limited | Professional & scientific | 2012 |
| Art & Sold Limited | Wholesale & retail | 2000 |
| Art Basket Ltd | Wholesale & retail | 2018 |
| Art for Investment Ltd | Arts & recreation | 2006 |
| Art of Electrics Ltd | Other services | 2020 |
| Artefact Coffee Ltd | Manufacturing | 2023 |
| Artefact Design Ltd | Extraterritorial | 2019 |
| Artemis Advanced Flying Training Ltd | Education | 2018 |
| Artemis Software Ltd | Information & communication | 2003 |
| Arthur & North Holdings Limited | Financial services | 2021 |
| Artifiscent Ltd | Manufacturing | 2019 |
| Artillery Mews Management Company Limited | Households | 1998 |
| Artizan Installations Limited | Construction | 2021 |
| Arwen AI Limited | Information & communication | 2020 |