| Roehampton University | Greater London |
| Roeville Computer Systems Ltd | South Yorkshire |
| RoEx | Greater London |
| Rohallion Ltd | East Lothian |
| ROI Designs | |
| ROI Digital Marketing Ltd | |
| Roke | Hampshire |
| Rokk | Devon |
| Roli | |
| Rolls-Royce plc | |
| Rom and Ram | Merseyside |
| RomanCart | Somerset |
| Romax Technology Ltd | Nottinghamshire |
| Ronins Group Ltd | |
| Roodee Web Design | Cheshire |
| Room 108 | |
| Room booking system | Glasgow |
| Rooser Ltd | |
| Root Solutions Ltd | Cambridgeshire |
| Root Studio | |
| RootsMagic UK | Wiltshire |
| Rootsol Ltd | North Yorkshire |
| RootstockLabs Ltd | |
| Roquefort Therapeutics plc | |
| Rosa Biotech Ltd | |
| Rose Bruford College | |
| Roseblade Media | Blaenau Gwent |
| Rosecut | |
| Rosemont Pharmaceuticals Ltd | |
| Rosie Lee Creative | |
| Roslin Design | Edinburgh |
| Roslin Technologies Ltd | |
| RoslinCT | |
| Rossiter & Co Ltd | Lancashire |
| Rosslyn Data Technologies plc | |
| Rossum | |
| RotaCloud | |
| Rotageek | |
| Rothamsted Research | |
| Roto | Greater London |
| ROUGE digital | |
| Rouge Media | Berkshire |
| RoukenBio | |
| Round Ash Associates | Devon |
| Roundtable | |
| Route Konnect Ltd | |
| Route Reports | |
| Route22 Ltd | Surrey |
| Routetrader Ltd | |
| Rover Electrica Ltd | Lancashire |