| Admire Elite UK Ltd | Real estate | 2021 |
| ADN Bridging & Commercial Finance Limited | Financial services | 2024 |
| Adnan Dent Ltd | Financial services | 2022 |
| Adrian Collins Limited | Information & communication | 1998 |
| Adrians Stone Works Limited | Manufacturing | 2025 |
| Adrzig DLV Ltd | Transport & logistics | 2021 |
| Adscap Ltd | Financial services | 2024 |
| Adscribe Ltd | Information & communication | 2023 |
| Adsense Digital Media Ltd | Information & communication | 2023 |
| Adson Construction Ltd | Construction | 2021 |
| Adson Holdings Ltd | Financial services | 2022 |
| Adson Maintenance Ltd | Construction | 2022 |
| Advance Medical Services Limited | Health & social care | 2011 |
| Advance Vending Services Limited | Hospitality | 1991 |
| Advanced Cooling Services Limited | Administrative & support | 2007 |
| Advanced Injury Management Limited | Health & social care | 2017 |
| Advanced Property Protection Limited | Construction | 2014 |
| Advanced Resource Managers Engineering Limited | Administrative & support | 2001 |
| Advanced Resource Managers IT Limited | Administrative & support | 1996 |
| Advanced Resource Managers Limited | Professional & scientific | 2004 |
| Advanced Resource Managers Training Limited | Professional & scientific | 2001 |
| Advanced Wireless Technology Limited | Professional & scientific | 2010 |
| Advantage Care Solutions Limited | Health & social care | 2019 |
| Adxmo Ltd | Wholesale & retail | 2025 |
| AE Baxter Holdings Ltd | Financial services | 2019 |
| AE Electrical (South) Ltd | Construction | 2022 |
| Aedex Ltd | Construction | 2026 |
| AEI Scaffolding Limited | Construction | 2016 |
| AEM Media Ltd | Professional & scientific | 2024 |
| Aemmos Ltd | Information & communication | 2012 |
| Aemyrie Holdings Limited | Manufacturing | 2018 |
| Aemyrie Limited | Manufacturing | 2016 |
| Aero GB Limited | Administrative & support | 2005 |
| Aeroviewtv Limited | Information & communication | 2023 |
| AES Hampshire Ltd | Extraterritorial | 2024 |
| Aesthetic Urns Ltd | Wholesale & retail | 2021 |
| AET Electrical Systems Ltd | Administrative & support | 2016 |
| AF & Sons Developments Ltd | Real estate | 2026 |
| AF Plumbing Limited | Construction | 2022 |
| AFC Portchester Enterprises Ltd | Arts & recreation | 2018 |
| AFC Portchester Holdings Limited | Arts & recreation | 2020 |
| AFC Portchester in the Community CIC | Arts & recreation | 2026 |
| AFC Portchester Limited | Arts & recreation | 2012 |
| Affinity Resource Partnerships Ltd | Administrative & support | 2021 |
| Affinity Solar Solutions Ltd | Wholesale & retail | 2023 |
| Afford a Print Limited | Manufacturing | 2023 |
| Affordable Secondhand Cars Limited | Wholesale & retail | 2018 |
| Afis (U.K.) Ltd | Other services | 2020 |
| Afrikana Event Ltd | Hospitality | 2025 |
| Afro Cart Limited | Wholesale & retail | 2013 |
| AFS Composites Ltd | Other services | 2024 |
| AFS Healthcare Limited | Health & social care | 2025 |
| Afterhours Group Ltd | Administrative & support | 2025 |
| AG Education & Training Ltd | Hospitality | 2014 |
| AG Travel & Tourism Ltd | Other services | 2016 |
| Ag-Search Limited | Administrative & support | 2017 |
| Agalsi Holdings Limited | Financial services | 2024 |
| Agalsi Investments Limited | Real estate | 2024 |
| Agalsi Properties Limited | Real estate | 2018 |
| Agameri Ltd | Information & communication | 2022 |
| Agar and Gregory Electrical Services Limited | Construction | 2010 |
| AGB Carpentry Limited | Construction | 2009 |
| Agency Payroll Limited | Professional & scientific | 2023 |
| Agilelens Ltd | Information & communication | 2025 |
| Agilita Workspace Limited | Wholesale & retail | 2019 |
| Agincourt Contractors Limited | Construction | 2002 |
| Agme Ltd | Construction | 2022 |
| Agni Properties Ltd | Real estate | 2020 |
| Agni Rentals Ltd | Real estate | 2022 |
| Agni Retails Ltd | Wholesale & retail | 2015 |
| Agnni Retails Ltd | Wholesale & retail | 2021 |
| AGR Group Limited | Financial services | 2016 |
| AGS Foods Limited | Hospitality | 2021 |
| AH Builders (South) Ltd | Construction | 2019 |
| AH Hand Car Wash Ltd | Administrative & support | 2016 |
| AH Subsea Ltd | Professional & scientific | 2023 |
| Ahexpress Ltd | Wholesale & retail | 2026 |
| Ahmed Capital Group Limited | Real estate | 2016 |
| Ahmed Kitchen Limited | Hospitality | 2025 |
| Ahoy Communications Ltd | Professional & scientific | 2025 |
| AHR Property Ltd | Real estate | 2018 |
| AI Edutech Limited | Information & communication | 2024 |
| AI Growth Accelerator Ltd | Information & communication | 2025 |
| AI Procurement Ltd | Information & communication | 2025 |
| AI Technical Ltd | Administrative & support | 2023 |
| AI3 Travel Limited | Transport & logistics | 2024 |
| AIB Transport Ltd | Transport & logistics | 2020 |
| Aibel Finance Limited | Financial services | 2006 |
| Aibel Group Limited | Financial services | 2003 |
| Aibel Holding Limited | Professional & scientific | 2003 |
| Aibel Limited | Professional & scientific | 2006 |
| AIF Marine Ltd | Construction | 2022 |
| Aikeda Education and Travel Ltd | Administrative & support | 2019 |
| Aintree Group Limited | Real estate | 2021 |
| Aintree Holdings Ltd | Financial services | 2021 |
| Airports Direct Limited | Transport & logistics | 1999 |
| Aitkins Interior Specialist Ltd | Construction | 2018 |
| AJ Knight Property Services Limited | Real estate | 2013 |
| AJ Power Solutions Ltd | Construction | 2024 |
| AJ Rudd Brickwork Ltd | Professional & scientific | 2020 |