| Ambrow Ltd | Nottinghamshire |
| Ambush Web Design | Greater London |
| Amcall Communications Ltd | Hampshire |
| AMD Web Design | West Midlands |
| Amdaris Group Ltd | |
| AME Solutions | Devon |
| Ameba Systems Ltd | |
| American Leaders for Leaders | Greater London |
| Amersham Websites | |
| Amethyst Consultancy | Lincolnshire |
| Amethyst Risk Management Ltd | Hampshire |
| AMFG | |
| AMG IT Solutions | Staffordshire |
| AMG Systems Ltd | Bedfordshire |
| AMI3GO Ltd | |
| Amigaworld.net | Belfast |
| Amigo Studios | |
| Amigoscode | |
| Amimetic | |
| Amine Dahimene - SEO Expert | |
| Amino Communications | |
| Amiqus Resolution Ltd | |
| Amito Ltd | Berkshire |
| AMJ UK | Kent |
| AML Analytics Ltd | |
| AML Technology | Dumfries and Galloway |
| AMLo Biosciences Ltd | |
| Ammara | Surrey |
| AMO Pharma Ltd | |
| Amoo | |
| AMP Computer Maintenance | |
| AMP Studio | |
| Amparo Prosthetics Ltd | |
| Amped Digital Ltd | |
| Amped PCR | |
| Ampersand & Ampersand | |
| AMPG IT Services | South Yorkshire |
| Amphin Ltd | |
| Amphis Software | Somerset |
| Amphista Therapeutics | |
| Amphora Software Ltd | |
| Amplicon Liveline Ltd | East Sussex |
| Amplience | |
| AmplifyMe | Aberdeen |
| Ampliphae | |
| Ampliphae | |
| Ampology Digital | |
| AMS Biotechnology | |
| Amshire Solutions Ltd | Greater Manchester |
| AMSIM | |