| Aimconsult Limited | Professional & scientific | 2003 |
| Aimpos Ltd | Wholesale & retail | 2018 |
| Ainsey's Entertainment Ltd | Administrative & support | 2018 |
| Aioma Limited | Wholesale & retail | 2025 |
| Aiops Forge Ltd | Information & communication | 2026 |
| Air for Life UK Ltd | Manufacturing | 2017 |
| Air Payroll Services Limited | Professional & scientific | 2020 |
| Air Sound Specialist Ltd | Administrative & support | 2023 |
| Air Travel Extras Limited | Administrative & support | 2024 |
| Aira Care and Support Services Limited | Health & social care | 2025 |
| Aira Digital Limited | Professional & scientific | 2014 |
| Airaero Colours Limited | Wholesale & retail | 2016 |
| Airband Wireless Limited | Information & communication | 2025 |
| Airborne Imaging Limited | Extraterritorial | 2015 |
| Aircraft Technical Consultancy Services Limited | Professional & scientific | 2010 |
| Aircyclone Purifier Systems Ltd | Other services | 2023 |
| Aireka Digital Transformation Ltd | Information & communication | 2026 |
| Airfarmer Ltd | Other services | 2024 |
| Airfins Ltd | Administrative & support | 2009 |
| Airgead Ltd | Administrative & support | 2020 |
| Airpixels Aerial Services Ltd | Professional & scientific | 2025 |
| Airport 2 Home Ltd | Transport & logistics | 2019 |
| Airport Connect MK Ltd | Transport & logistics | 2022 |
| Airport Express MK Ltd | Transport & logistics | 2012 |
| Airport Facility Management Ltd | Administrative & support | 2020 |
| Airport Systems Engineering Limited | Professional & scientific | 2017 |
| Airport Vehicle Services Limited | Wholesale & retail | 2011 |
| Airrigation Ltd | Other services | 2024 |
| Airroc Limited | Manufacturing | 2016 |
| Airstudios Ltd | Arts & recreation | 2023 |
| Airtask Group Limited | Transport & logistics | 1979 |
| Airwave Services Limited | Information & communication | 1998 |
| Aishwaa Consulting Ltd | Information & communication | 2022 |
| Aisprk Ltd | Administrative & support | 2025 |
| Aives Forward Limited | Financial services | 2014 |
| AJ Accountants & Tax Consultants Ltd | Professional & scientific | 2017 |
| AJ Avionics Ltd | Manufacturing | 2026 |
| AJ Bell Property Ltd | Real estate | 2025 |
| AJ Power Cleaning Ltd | Administrative & support | 2025 |
| AJ Psych Ltd | Health & social care | 2024 |
| AJ Tech City Holdings Ltd | Financial services | 2023 |
| AJA Functions Limited | Hospitality | 2018 |
| Ajaawa Ltd | Wholesale & retail | 2026 |
| Ajai Technology Holdings Limited | Information & communication | 2021 |
| Ajax Blockchain Limited | Information & communication | 2021 |
| AJB Construction & Roofing Ltd | Construction | 2024 |
| AJB Dental Ltd | Health & social care | 2020 |
| AJB Property Ltd | Real estate | 2018 |
| AJB Quantity Surveying Ltd | Construction | 2020 |
| AJB Solutions Ltd | Professional & scientific | 2026 |
| AJB Strategy Ltd | Financial services | 2011 |
| AJC Interiors (London) Limited | Manufacturing | 2019 |
| AJC Transport Ltd | Wholesale & retail | 2025 |
| Ajcor Group Ltd | Financial services | 2025 |
| AJCREAT3D Ltd | Construction | 2024 |
| Ajcw Medical Services Limited | Health & social care | 2019 |
| AJE Operations Limited | Administrative & support | 2014 |
| AJG Contracting Limited | Construction | 2023 |
| AJH Consultancy MK Ltd | Professional & scientific | 2023 |
| AJH Landscape Solutions Limited | Administrative & support | 2025 |
| Ajhs Services Limited | Wholesale & retail | 2024 |
| AJM Healthcare Group Limited | Financial services | 2018 |
| AJM Healthcare Limited | Administrative & support | 2018 |
| AJN Resourcing Ltd | Professional & scientific | 2023 |
| AJN Student Properties Ltd. | Manufacturing | 2015 |
| AJN Trading Limited | Wholesale & retail | 2020 |
| AJO Communications Ltd | Information & communication | 2024 |
| AJO Holding Ltd | Wholesale & retail | 2019 |
| AJR10 Limited | Wholesale & retail | 2025 |
| AJS Aviation Limited | Manufacturing | 2008 |
| Ajsk Estates Ltd | Real estate | 2022 |
| Ajsl Construction Ltd | Construction | 2014 |
| Ajtan Limited | Construction | 2006 |
| AJW Eales Ltd | Construction | 2024 |
| AJW Property Limited | Real estate | 2016 |
| AK & TA Radcliffe Limited | Hospitality | 2024 |
| AK Beauty Limited | Health & social care | 2015 |
| AK Body Repair Ltd | Construction | 2023 |
| AK Groundworks Ltd | Construction | 2026 |
| AK Plumbing & Heating Limited | Construction | 2019 |
| AK Star Ltd | Arts & recreation | 2025 |
| AK Trading Distribution Ltd | Wholesale & retail | 2023 |
| AK3D Printing Shop UK Ltd | Manufacturing | 2023 |
| AKA Dynamics Ltd | Health & social care | 2023 |
| AKA London Limited | Real estate | 2023 |
| Akal Global Logistics Ltd | Transport & logistics | 2021 |
| Akanksha Consultants Ltd | Information & communication | 2024 |
| Akasaka Holding Ltd | Hospitality | 2016 |
| Akasaka MK Ltd | Hospitality | 2013 |
| AKC TEK Services Ltd | Professional & scientific | 2017 |
| Akcess CIC | Transport & logistics | 2004 |
| Akef Care Solutions Ltd | Health & social care | 2025 |
| Akefny Services Limited | Health & social care | 2022 |
| Akeley Joinery Ltd | Manufacturing | 2021 |
| Akeno Limited | Other services | 2015 |
| AKG (UK) Employment Limited | Administrative & support | 2020 |
| AKG (UK) Health Limited | Professional & scientific | 2022 |
| AKH Hand Car Wash Ltd | Wholesale & retail | 2019 |
| Akhand Armour Ltd | Wholesale & retail | 2020 |
| Akhtar's Auto Centre Limited | Wholesale & retail | 2019 |