| Affinity Legal Services Ltd | Other services | 2001 |
| Affinity Wills Ltd | Professional & scientific | 1999 |
| Affinity Wills Services Ltd | Professional & scientific | 1999 |
| Affinity Willsafe Limited | Transport & logistics | 2002 |
| African Farming Union Ltd | Other services | 2026 |
| Afriponds Limited | Construction | 2019 |
| AG Fences and Gates Ltd | Agriculture & fishing | 2025 |
| AGE UK East Grinstead & District | Health & social care | 2008 |
| Agentu Ltd | Information & communication | 2025 |
| Agile Companion Technologies Ltd | Information & communication | 2020 |
| Agio Interactive Limited | Information & communication | 2010 |
| Agrilift (UK) Limited | Administrative & support | 2003 |
| Aidan Aero Services Ltd | Manufacturing | 2010 |
| Aile Land & Planning Limited | Construction | 2022 |
| Air West Limited | Transport & logistics | 1987 |
| Airconsult Limited | Extraterritorial | 2013 |
| Airtec Air Conditioning Limited | Extraterritorial | 2015 |
| Airtec Air Conditioning Services Limited | Extraterritorial | 2015 |
| Airtech (Service & Maintenance) Limited | Other services | 1982 |
| Airtech Air Conditioning & Climate Control Limited | Extraterritorial | 2015 |
| Airtech Air Conditioning Limited | Extraterritorial | 2015 |
| Airtech Air Conditioning Services Limited | Construction | 1980 |
| Airtech Building Services Limited | Extraterritorial | 2015 |
| Airtech Environmental Limited | Extraterritorial | 2015 |
| Airtech Environmental Services Limited | Extraterritorial | 2015 |
| Airtech Facilities Management Limited | Extraterritorial | 2015 |
| Airtech FM Limited | Extraterritorial | 2015 |
| Airtech Heating Limited | Extraterritorial | 2015 |
| Airtech Installations Limited | Extraterritorial | 2015 |
| Airtech Limited | Administrative & support | 1997 |
| Airtech Mechanical Services Limited | Extraterritorial | 2015 |
| Airtech Services Limited | Extraterritorial | 2015 |
| Airtech Special Products Limited | Construction | 1992 |
| Airteck Limited | Extraterritorial | 2019 |
| Aisle and Beyond Ltd | Professional & scientific | 2021 |
| AJ Malik Ltd | Wholesale & retail | 2025 |
| AJG Waters (Equipment) Limited | Wholesale & retail | 1991 |
| Akehurst Construction Ltd | Construction | 2011 |
| Akorn Recruitment Limited | Administrative & support | 2000 |
| AL Oakmont Ltd | Administrative & support | 2024 |
| Alan Fellows Associates Limited | Administrative & support | 2009 |
| Alan Rogers Guides Limited | Information & communication | 2023 |
| Alan Rogers Travel Group Limited | Administrative & support | 2001 |
| Alan Rogers Travel Limited | Administrative & support | 1998 |
| Albourne Irrigation Services Limited | Construction | 2002 |
| Alchemy Care London Limited | Wholesale & retail | 2015 |
| Alex Bennett Marketing Services Limited | Professional & scientific | 2024 |
| Alex Nash Limited | Construction | 2013 |
| Alexander Charles Exquisite Bathrooms Ltd | Construction | 2022 |
| Alexandria Gardens Limited | Construction | 2019 |
| Alfavox Ltd | Wholesale & retail | 2023 |
| Alfreton Properties Ltd | Financial services | 2022 |
| Alignment Film Productions Limited | Professional & scientific | 2024 |
| ALL Day Landscapes Limited | Other services | 2025 |
| ALL Electric Services Ltd | Construction | 2021 |
| ALL OUR Bars Limited | Hospitality | 2010 |
| ALL Speed Clutches and Brakes Limited | Wholesale & retail | 1987 |
| ALL Your Hospitality Services Limited | Hospitality | 2010 |
| Allan Hayes Engineering Limited | Manufacturing | 1977 |
| Allspeed DS Limited | Professional & scientific | 2007 |
| ALN & Associates Ltd | Professional & scientific | 2005 |
| Alpha Extra Space Ltd | Construction | 2014 |
| Alsaraj Ltd | Health & social care | 2024 |
| Altering Ltd | Information & communication | 2024 |
| Altitude Consultants Limited | Professional & scientific | 2009 |
| Altitude Events Limited | Arts & recreation | 2012 |
| Altolofts Ltd | Construction | 2021 |
| AM Conference Production Ltd | Administrative & support | 2022 |
| Amadeus Computer Supplies Limited | Wholesale & retail | 1994 |
| Amaia Limited | Construction | 2012 |
| AMB Roofing Services Limited | Construction | 2024 |
| Amber Crest Properties Ltd | Real estate | 2025 |
| Amelioris Consulting Ltd | Information & communication | 2011 |
| Amethyst AGE Art Limited | Information & communication | 2013 |
| Amigo Business Ltd | Wholesale & retail | 2017 |
| Amlybuild Limited | Construction | 2008 |
| Amoricana Limited | Hospitality | 2025 |
| Ampersand Collective Ltd | Education | 2026 |
| Amulet Creative Ltd | Information & communication | 1999 |
| AMZ Source Limited | Other services | 2018 |
| Anawa Limited | Administrative & support | 2026 |
| Anchor Industrial Coatings Ltd | Construction | 2023 |
| Anderham Investment Limited | Hospitality | 2011 |
| Andrew Farmer Property Ltd | Real estate | 2026 |
| Angelika and Angelique Ltd | Health & social care | 2019 |
| Anibles Ltd | Arts & recreation | 2022 |
| Anish’S Property Investment Ltd | Real estate | 2022 |
| Anker Property Ltd | Real estate | 2024 |
| Ankerton Business Development Ltd | Professional & scientific | 2017 |
| Ann's Orchard Limited | Wholesale & retail | 2013 |
| Anna Mason Art Limited | Wholesale & retail | 2015 |
| Annet Technologies (Europe) Limited | Information & communication | 2014 |
| Antalis Enterprises Ltd | Information & communication | 2012 |
| Antares Wood Floors Limited | Construction | 2008 |
| Antoniou Holdings Ltd | Financial services | 2026 |
| Antoniou Leggett Ltd | Real estate | 2025 |
| Antrobus Housing Ltd | Real estate | 2025 |
| ANZ Property Investments Limited | Real estate | 2024 |
| Aogg Payroll Ltd. | Administrative & support | 2023 |
| AP Valves and Services UK Ltd | Wholesale & retail | 2019 |