| Amsys Ltd | Greater London |
| AMT Auto | |
| AMT Data Technologies Ltd | Hampshire |
| Amuzo Ltd | Dorset |
| AMX Solutions Ltd | |
| AN4 Group Ltd | Hampshire |
| AnaCap | |
| Anachron Technologies Ltd | |
| Anagram Systems Ltd | |
| Analog Studio | |
| Analogue Integration Ltd | Wiltshire |
| Analox Instruments Ltd | |
| Analyse-it | West Yorkshire |
| Analysys Mason | |
| Analytical Services International | |
| Analytical Technology and Control Ltd | Wiltshire |
| Analytics Engines | |
| Anamosys | |
| Ananda Web Ltd | |
| Anaphite Ltd | |
| Anastasis Biotec Ltd | |
| Anatec BI | Berkshire |
| Anatomise Biostats | |
| ANB Software Ltd | South Yorkshire |
| Ancoris Ltd | Berkshire |
| And Again Ltd | |
| And Another Day Ltd | |
| AND Digital | |
| Andalay Technologies | |
| Anders Analytics Ltd | |
| Anderson IT Consulting | Oxfordshire |
| Anderson Stockley Accredited Training Ltd | |
| Andica Ltd | Buckinghamshire |
| Andover College | |
| Andpartnership | |
| Andre Armacollo | Greater London |
| Andrew Backhouse | |
| Andrew Burdett Design | Derbyshire |
| Andrew Lock | |
| Andrew Wills Web Developer | |
| Andrews & Arnold Ltd | Berkshire |
| Andrews Computer Services Ltd | Hertfordshire |
| Andy Morley | Derbyshire |
| Andy Pike Ltd | Surrey |
| Anexsys Ltd | |
| Angel Digital Marketing | Nottinghamshire |
| Angel Investment Network Ltd | |
| Angel Solutions Ltd | Merseyside |
| Angell & Co. | |
| Angello | |