| Ahdesmaki Information Consulting and Professional Services Limited | Professional & scientific | 2023 |
| Ahdk Health Ltd | Wholesale & retail | 2024 |
| Ahead Only Limited | Real estate | 2026 |
| AHG Orthodontics Ltd | Health & social care | 2012 |
| Ahlan Arabic Ltd | Education | 2017 |
| Ahluwalia Education & Consulting Ltd | Education | 2016 |
| Ahmed Zaidi Ltd | Professional & scientific | 2020 |
| Ahren II LP | | 2022 |
| Ahren Innovation Capital (GP) II LLP | | 2022 |
| Ahren Innovation Capital LLP | | 2017 |
| Ahren LP | | 2018 |
| Ahse Property Limited | Real estate | 2025 |
| AI & Human Empowerment CIC | Professional & scientific | 2025 |
| AI Harmony Labs Limited | Information & communication | 2025 |
| AI Jameson Group (UK) Co., Ltd | Administrative & support | 2018 |
| AI Machines Limited | Information & communication | 2015 |
| AI Meta Club Ltd | Wholesale & retail | 2023 |
| AI Nolutech Ltd | Manufacturing | 2023 |
| AI Publishing Solutions Ltd | Information & communication | 2022 |
| AI Quanting Ltd | Information & communication | 2025 |
| AI Sequrity Ltd | Information & communication | 2025 |
| AIA (Cambridge) Ltd | Financial services | 2005 |
| AIA (ST Neots) Ltd | Financial services | 2020 |
| AIA Lifetime Ltd | Financial services | 2024 |
| Aiask Limited | Information & communication | 2024 |
| Aiasst. Ltd | Extraterritorial | 2020 |
| Aicomp UK Limited | Information & communication | 2017 |
| Aida Innovation Ltd | Professional & scientific | 2024 |
| Aigiri Technology Ltd | Information & communication | 2022 |
| Aila Biotech Ltd | Professional & scientific | 2021 |
| Ailsa Court Management Limited | Real estate | 1982 |
| Aimax Axis Limited | Professional & scientific | 2025 |
| Aime Consulting Ltd | Professional & scientific | 2016 |
| Aimkick Ltd | Information & communication | 2024 |
| Ainsworth Place Ltd | Households | 2018 |
| AIOANEI22 Ltd | Manufacturing | 2025 |
| Aios AI Ltd | Information & communication | 2021 |
| Aipolas Limited | Professional & scientific | 2012 |
| Air BEE Clean Limited | Administrative & support | 2025 |
| Air Broadband Limited | Information & communication | 2013 |
| Air Hunter Ltd | Manufacturing | 2026 |
| Air Next Ltd | Manufacturing | 2023 |
| Air Source Cambridge Limited | Construction | 2023 |
| Air Support Staff Ltd | Manufacturing | 2026 |
| Air Tech Mechanic Ltd | Manufacturing | 2026 |
| Air-Sep Ltd | Manufacturing | 2023 |
| Airaviontech Ltd | Manufacturing | 2025 |
| Airbow Ltd | Manufacturing | 2024 |
| Aircraft Adventure Ltd | Manufacturing | 2025 |
| Aircraft Engineering Solutions Ltd | Manufacturing | 2024 |
| Aircraft Spares & Materials Limited | Administrative & support | 1998 |
| Aircraft Structures Ltd | Manufacturing | 2025 |
| Aire Valley Cleaning Division Limited | Administrative & support | 2025 |
| Airfirm Ltd | Manufacturing | 2026 |
| Airflow Tech Ltd | Wholesale & retail | 2018 |
| Airfly Limited | Manufacturing | 2023 |
| Airforce Engineering Ltd | Manufacturing | 2023 |
| Airlinenuta Ltd | Manufacturing | 2026 |
| Airpoint RTM Company Limited | Households | 2011 |
| Airponix Ltd | Agriculture & fishing | 2014 |
| Airserve Limited | Administrative & support | 2018 |
| Airsource Ltd. | Information & communication | 2003 |
| Airtel (U.K.) Ltd | Information & communication | 2025 |
| Airvic Consultancy Ltd | Administrative & support | 2008 |
| Aisha Accounting Services Ltd | Professional & scientific | 2025 |
| Aitropolis Technologies Ltd | Information & communication | 2023 |
| Aiuto Properties Limited | Real estate | 2021 |
| AIV Homes Limited | Real estate | 2015 |
| Aivivo Ltd | Professional & scientific | 2017 |
| Aixcell Limited | Manufacturing | 2019 |
| Aixtron Limited | Manufacturing | 1999 |
| Aiza One Group Limited | Administrative & support | 2019 |
| AJ IT Solutions PVT Ltd | Information & communication | 2016 |
| AJ Martin Ltd | Wholesale & retail | 2017 |
| AJB Invest Limited | Real estate | 2016 |
| AJD Property Group Limited | Real estate | 2018 |
| Ajdaesthetics Ltd | Health & social care | 2009 |
| Ajge Limited | Financial services | 2023 |
| AJH Accounting Ltd | Financial services | 2020 |
| AJH Investments (Cambridge) Limited | Financial services | 2023 |
| AJK Recycling Solutions Limited | Water & waste | 2012 |
| AJM Global Trading Ltd | Manufacturing | 2024 |
| Ajmmynt Limited | Real estate | 2008 |
| AJP Business Finance Solutions Ltd | Financial services | 2024 |
| Ajsc Properties Limited | Real estate | 2015 |
| Ajsfuture Ltd | Information & communication | 2024 |
| AJV Aerospace Ltd | Manufacturing | 2026 |
| AK Cambridge Properties Ltd | Real estate | 2024 |
| Akarana Limited | Mining & quarrying | 1997 |
| Akasha Dance Theatre Ltd. | Arts & recreation | 2017 |
| AKB Aerospace Ltd | Manufacturing | 2016 |
| AKC Windows Limited | Construction | 2017 |
| Akcio Management Consulting Ltd | Professional & scientific | 2021 |
| Akeman Dental Ltd | Health & social care | 2022 |
| Akendi UK Limited | Information & communication | 2012 |
| Akimeter Technology Co., Ltd | Extraterritorial | 2018 |
| Akisha Consulting Ltd | Professional & scientific | 2015 |
| Akisha Property Limited | Real estate | 2017 |
| Akmazo Health Ltd | Professional & scientific | 2022 |
| Akmiller Technologies Limited | Information & communication | 2019 |