| Loughborough University - School of Mathematics | Leicestershire |
| Louis Websdale | |
| Louth Computer Shop | Lincolnshire |
| Love&Logic | |
| Loveelectric | Edinburgh |
| lovehtml | |
| Lovell Developments Ltd | |
| Low Observable Technology Ltd | |
| Low&Behold | |
| Low6 Ltd | |
| LowerCall UK | Bristol |
| Loxit Ltd | Cheshire |
| Loyalty Matters Ltd | North Yorkshire |
| Loyalty UK | Greater London |
| LPD Electronic Services Ltd | Suffolk |
| LPS Ltd | |
| LRJ Solutions | |
| LRQA Group Ltd | West Midlands |
| LS25 Web Hosting | |
| LSA Systems Ltd | Essex |
| LSA Technology | Greater Manchester |
| Ltdonline Ltd | Warwickshire |
| LTF Design & Marketing Ltd | |
| Lua Website Design | Devon |
| Lucas Power & Control Ltd | Edinburgh |
| Lucent | |
| Lucent Biopharma | |
| Lucid Computer Solutions | |
| Lucid Games Ltd | |
| Lucid Group Ltd | |
| Lucid IT Solutions | West Yorkshire |
| Lucid Networks | |
| Lucid Systems | |
| Lucid Technology Solutions | County Durham |
| Lucidata Data Communications Consultants | Cambridgeshire |
| Lucky Duck | West Yorkshire |
| LuckyTrip | |
| Luckywebs | |
| Ludger Ltd | |
| Lugo Ltd | West Lothian |
| Luhhu Ltd | |
| Luma Information Systems | Hampshire |
| LUMA-iD Ltd | |
| Lumen Digital | |
| Lumen Ventures | |
| Lumi Studio | |
| Lumico Digital Ltd | |
| Luminal | |
| Luminance Technologies Ltd | Greater London |
| Luminary Brands | |