| Avantgarde | |
| 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 |
| aVaxMed Ltd | |
| aVaxziPen | |
| Avaza Ltd | Isle of Man |
| AVC Immedia | |
| AVC Weeeco Ltd | |
| AVCO Systems Ltd | Berkshire |
| Ave Design Studio | |
| Avec Solutions | Belfast |
| avecSys | |
| Aveni | |
| Avenista | Cheshire |
| Avenna Ltd | |
| Aventus Platform Ltd | |
| Avestu Capital, LLP | |
| AVEVA Group plc | Cambridgeshire |
| Avexia | Hampshire |
| AviadoBio Ltd | |
| AviaSoft Ltd | Greater London |
| Avid Panda | |
| AVID plc | East Sussex |
| Avida Global Ltd | |
| AVIDI Technologies | |
| Avieco | |
| Avillion Life Sciences | |
| Avillion, LLP | |
| Avipero Ltd | |
| Aviva | Greater London |
| Avizent Network Solutions | |
| Avnio | |
| Avoen | |
| Avon Computer Co-operative Ltd | Wiltshire |
| Avon Data | |
| Avonline Networks | |
| Avontus Software Corporation | Cambridgeshire |
| Avonwood Developments Ltd | Dorset |
| Avora | Greater London |
| Avrion | Hertfordshire |
| avrmobiles.co.uk Ltd | Hertfordshire |
| AVUXI | Greater London |
| AVW Controls Ltd | |
| AVY Consultancy Ltd | |