| Paramount Digital | |
| Paramount Electronics Ltd | Buckinghamshire |
| Parasym Ltd | |
| Paravail Ltd | Gloucestershire |
| Parcelly Ltd | |
| Parentapps | |
| Parfin | |
| Pario Ventures | |
| Parity Technologies | |
| Park Square Consulting Ltd | |
| Parker Design Consultants Ltd | |
| Parker Shaw | Hampshire |
| Parker Software Ltd | Staffordshire |
| Parkglobe Consultants Ltd | West Sussex |
| Parkhouse Evans Ltd | Derbyshire |
| ParkinsonHowe | Greater Manchester |
| Parkspace | Berkshire |
| Parkure | |
| Parkwalk | |
| Parseq | South Yorkshire |
| Parsley Box Ltd | |
| Part Four | |
| Partisan | |
| PartitionBio | |
| PartitionBio | |
| Partner Rare | |
| Partner Rare | |
| Partners Capital Investment Group, LLP | |
| Partners in Training | North Yorkshire |
| PartnerSoft Ltd | Renfrewshire |
| Pasabi | |
| Passby Technologies Ltd | |
| Passenger Technology Group Ltd | Dorset |
| Passion Capital | |
| Passion Capital | |
| Passion Digital | Greater London |
| Passle Ltd | |
| Paston Chase Ltd | Norfolk |
| Patchsave Solutions | Hertfordshire |
| Patchworks | |
| Pathfinder Medical | |
| Pathios Therapeutics Ltd | |
| Pathmaker Dev Ltd | |
| Pathway UK Ltd | Merseyside |
| Patients Know Best | |
| Patrick Internet | Somerset |
| Patrick Molyneux | Gloucestershire |
| Patrick Thorn & Co. | Berkshire |
| Patron Capital | |
| Patton Filson | |