| Addedlovely Ltd | Information & communication | 2014 |
| ADM Soft Labs Limited | Wholesale & retail | 2014 |
| ADM Supllies Ltd. | Wholesale & retail | 2024 |
| Admo Services Limited | Construction | 2018 |
| Adorn Design Studio Limited | Other services | 2018 |
| ADR Estates Limited | Real estate | 2019 |
| Adrarn Ltd | Real estate | 2018 |
| Adroit Construction Ltd | Construction | 2015 |
| Advanced Data Spectrum Limited | Information & communication | 1998 |
| Advanced Sensors and AI Ltd | Manufacturing | 2025 |
| Advantage Media Solutions Ltd | Information & communication | 2012 |
| Aegis Training Ltd | Arts & recreation | 2005 |
| Aern Design Limited | Professional & scientific | 2016 |
| Aesthetics by Claire Ltd | Other services | 2025 |
| AFE Design and Build Limited | Construction | 2016 |
| AFE Properties Limited | Real estate | 2018 |
| Afpa Limited | Information & communication | 2016 |
| Agile in Style Limited | Information & communication | 2015 |
| AGM Family Properties Limited | Real estate | 2024 |
| Aiecl Ltd | Information & communication | 2025 |
| Aimee Adams Consultants Limited | Professional & scientific | 2023 |
| Ainsley Renovations Limited | Construction | 2017 |
| Ainsworth & Wells Ltd | Professional & scientific | 2012 |
| Air & Water Consultants Limited | Administrative & support | 1998 |
| Airr Limited | Hospitality | 2022 |
| AJ Car Sales Ltd | Wholesale & retail | 2026 |
| AJ Cars and Vans Ltd | Wholesale & retail | 2018 |
| AJF Associates Limited | Professional & scientific | 2013 |
| AJP Electrics Ltd | Construction | 2014 |
| AK Adventures Ltd | Information & communication | 2019 |
| AK Music Ventures Ltd | Information & communication | 2023 |
| Akam 2025 Ltd | Financial services | 2025 |
| Akam Ltd | Real estate | 2026 |
| Akeia AI Ltd | Information & communication | 2025 |
| Alac Services Limited | Arts & recreation | 2019 |
| Alan Rigby Associates Limited | Professional & scientific | 2011 |
| Albany Professional Services Limited | Real estate | 1991 |
| Albion Estates Limited | Agriculture & fishing | 2018 |
| Aldeburgh Comedy Weekend Limited | Arts & recreation | 2025 |
| Aleksandra King Limited | Professional & scientific | 2014 |
| Alert Driving School Limited | Education | 2025 |
| Alex Residential Ltd | Real estate | 2024 |
| Alexa Bakes Ltd | Manufacturing | 2023 |
| Alexander - Churchill LLP | | 2009 |
| Alexander Construction Ltd. | Construction | 1992 |
| Alexander-Churchill Accountants Limited | Professional & scientific | 2015 |
| Alexson Developments Limited | Construction | 1984 |
| Algoritmi Technology Group Limited | Information & communication | 2026 |
| Alibaba Courier Ltd | Transport & logistics | 2020 |
| Alicialeckie Ltd | Professional & scientific | 2024 |
| Alien Wars Entertainment Ltd | Arts & recreation | 2024 |
| Alion Homes Ltd | Real estate | 2020 |
| ALL Building Solutions Limited | Construction | 1997 |
| ALL Go Skip and Grab Ltd | Water & waste | 2024 |
| ALL Letting Solutions Limited | Real estate | 2004 |
| ALL One Properties Ltd | Administrative & support | 2016 |
| ALL Round Fire & Security Ltd | Administrative & support | 2017 |
| ALL Spring Media Limited | Education | 2011 |
| All-Clear Drainage Limited | Water & waste | 2003 |
| Allbro BC Limited | Construction | 2017 |
| Allcover Financial Services Ltd | Financial services | 2021 |
| Allen Assets Ltd | Financial services | 2020 |
| Alliance Mobile Security Limited | Administrative & support | 1999 |
| Allmarsh Limited | Professional & scientific | 1988 |
| Allstar Capital Limited | Real estate | 2019 |
| Alouette Developments Limited | Construction | 2020 |
| Alouette Drylining Limited | Construction | 2013 |
| Alouette Property Limited | Real estate | 2025 |
| Alpesh Property Limited | Real estate | 2017 |
| Alpha Accident Claims Limited | Real estate | 2007 |
| Alpha Motoring Group Limited | Wholesale & retail | 2023 |
| ALPHA4ALL Limited | Education | 2013 |
| Alphabet Westbourne Holdings Limited | Financial services | 2026 |
| Alsama Limited | Hospitality | 2015 |
| Altaluna Ltd | Professional & scientific | 2018 |
| Altana Recruitment Ltd | Administrative & support | 2016 |
| Altered Image Chesham Limited | Other services | 2001 |
| Altered Image Limited | Other services | 2001 |
| Alternative Coaching Limited | Health & social care | 2016 |
| Aly's Supermarket Ltd | Wholesale & retail | 2025 |
| Alya Luna and Co Ltd | Wholesale & retail | 2026 |
| Amal Capital Limited | Real estate | 2025 |
| Amanaska Advisory Limited | Administrative & support | 2008 |
| Ambient Assisted Living Limited | Professional & scientific | 2011 |
| Ambyn Electrical Limited | Construction | 2011 |
| Amco Ventures Limited | Other services | 2018 |
| Amelux Limited | Real estate | 2014 |
| Amersham Blinds Limited | Wholesale & retail | 2007 |
| Amersham Deanery Trust | Other services | 2012 |
| Amersham Decorating Supplies Limited | Wholesale & retail | 2014 |
| Amersham WG Holdings Ltd | Financial services | 2024 |
| Amersham Window & Door Company Limited | Construction | 2012 |
| Amin Saleh Ltd | Professional & scientific | 2017 |
| Amps Rail Limited | Arts & recreation | 2007 |
| Amptrad Limited | Health & social care | 2005 |
| Ampy Chesham Hill Ltd | Professional & scientific | 2025 |
| Ampy Chesham Ltd | Professional & scientific | 2025 |
| AMV Link Limited | Administrative & support | 2021 |
| AMY Angold Limited | Arts & recreation | 2017 |
| ANA Martinez Designs Limited | Administrative & support | 2004 |