| Autoclock Systems Ltd | |
| Autocom Products | Cambridgeshire |
| AutoConvert | |
| Autodata Products Ltd | |
| AutogenAI | |
| Autographic Insight | |
| Autolus Therapeutics | Greater London |
| Automarine UK Ltd | |
| Automata | |
| Automated Intelligence Ltd | Belfast |
| Automated Marketing System | Greater London |
| AutomatePro Ltd | |
| Automation Solutions Ltd | Surrey |
| Automation Systems Integrators Ltd | |
| Automation Technologies Ltd | |
| Automations IO Ltd | |
| Autometers Systems Ltd | |
| Automise | |
| Automotive Software Solutions | |
| Automotive Transformation Group | |
| Autone | |
| Autonomic Co-operative Ltd | |
| Autonomous Flight | |
| Autopage Ltd | Norfolk |
| Autoplus | Cornwall |
| AutoRek | Glasgow |
| Autoscript | Greater London |
| Autus Digital Agency UK | |
| AV Parts Master Ltd | Berkshire |
| AVA CAD/CAM Group Ltd | Cheshire |
| Avacta Life Sciences Ltd | |
| Avandda Ltd | Cheshire |
| Avantek Computer Ltd | Leicestershire |
| Avanti Business Software Ltd | |
| Avanti Hylas 2 Ltd | |
| Avanti PC Repairs | |
| Avantis World | Cardiff |
| Avantus Systems Ltd | |
| Avara Web Marketing | Hampshire |
| Avasa AI | |
| Avatu Ltd | Buckinghamshire |
| aVaxziPen | |
| Avaza Ltd | Isle of Man |
| AVC Immedia | |
| AVC Weeeco Ltd | |
| AVCO Systems Ltd | Berkshire |
| Ave Design Studio | |
| Avec Solutions | Belfast |
| avecSys | |
| Aveni | |