| Ocean Colour Scene | 1990 | — | — |
| Ocean Red | 1 December 2010 | — | — |
| Oceans Ate Alaska | 2011 | — | — |
| Odium | 1998 | — | — |
| Odyssey | 1968 | — | originally US family act Lopez Sisters, now UK fronted by Steven Collazo |
| Oh Wonder | 2014 | — | — |
| Ohhms | 2014 | — | — |
| Old Corpse Road | 2007 | — | — |
| Old Forest | 1998 | — | — |
| Old Radio | April 2011 | — | — |
| Old Swing | 2017 | — | — |
| Omega Tribe | 1981 | — | — |
| Ommadon | 2008 | — | — |
| Omnimalevolent | 2 September 2025 | — | — |
| On Parole | 1979 | — | — |
| One Dimensional Creatures | 2023 | — | — |
| One Way System | 1979 | — | — |
| Onslaught | 1983 | — | — |
| Opia | 2022 | — | — |
| Oppress. | 2016 | — | — |
| Opus Kink | 2017 | — | — |
| Orchestral Manoeuvres in the Dark | 1977 | — | — |
| Orpheum | 1 January 2010 | — | — |
| Osibisa | 1969 | — | — |
| Ostara | 1999 | — | — |
| Oswald | 15 May 2005 | — | — |
| Otalgia | 1985 | — | — |
| Outfit | 14 January 2011 | — | — |
| Outl4w | May 2004 | — | — |
| Outside Your House | 1 April 2014 | — | — |
| P.A.I.N | 1995 | — | — |
| P.M.T. | 1992 | — | — |
| Padded Cell | 2002 | — | — |
| Pagan Altar | 1978 | — | — |
| PagesEND | 2005 | — | — |
| Palace | September 2012 | — | — |
| Pallas | 1980 | — | UK progressive rock |
| Panchiko | 1997 | — | — |
| Panic Room | 2005 | — | — |
| Pantheist | 2000 | — | — |
| Paper Lace | 1969 | — | — |
| Paradise Lost | 26 March 1988 | — | British metal / hard rock band |
| Paralex | 1977 | — | — |
| Parallax | 1 October 2019 | — | — |
| Part 1 | 1980 | — | — |
| Part Chimp | 2000 | — | — |
| Party Cannon | 2010 | — | — |
| Pascal Farful Band | 2015 | — | — |
| Patterns | 2010 | — | — |
| Peace | 2009 | — | — |
| Peasant's King | 1 January 2012 | — | — |
| Peckeruk | 9 May 1998 | — | — |
| Penance Stare | 2017 | — | — |
| Pendleton | 2001 | — | — |
| Pendragon | 1976 | — | UK progressive rock |
| Penetration | 1976 | — | — |
| Percy | 1 May 1996 | — | — |
| Pet Crow | 2016 | — | — |
| Pet Slimmers of the Year | January 2008 | — | — |
| Peter Hook & the Light | May 2010 | — | — |
| Phase | 16 December 2004 | — | — |
| Phatt Knappii | 2012 | — | — |
| Phoenix Gene | 22 July 2012 | — | — |
| PIG | 1988 | — | — |
| Pig Irön | 2001 | — | UK-based rock band |
| Pigs Pigs Pigs Pigs Pigs Pigs Pigs | 2012 | — | — |
| Pink Hearse | 2005 | — | — |
| Pitchshifter | 1989 | — | — |
| Planet Noir | 2025 | — | — |
| Pneumania | 1979 | — | — |
| POG | 2000 | — | — |
| Polarsets | 1 December 2008 | — | — |
| Polymath | 2007 | — | — |
| Popes of Chillitown | 2009 | — | — |
| Porcupine Tree | 1987 | — | — |
| Portent | 2005 | — | — |
| Portishead | 1991 | — | — |
| Postmortem Promises | 2006 | — | — |
| Potential Threat | 1981 | — | — |
| Praecantator | 2016 | — | — |
| Prairies | 1 May 2011 | — | — |
| Pram | 1990 | — | — |
| Praying Mantis | 1974 | — | UK rock/metal band |
| Prefab Sprout | 1978 | — | — |
| PRESIDENT | 2025 | — | — |
| Pretenders | March 1978 | — | English‐American rock band |
| Pretty Vicious | 2014 | — | — |
| Primal Rock Rebellion | 2011 | — | — |
| Primal Scream | 1982 | — | Scottish rock band |
| Primitive Knot | 2014 | — | — |
| Prinzhorn Dance School | 2004 | — | — |
| Pro-jekt | January 2001 | — | — |
| Profiler | 2017 | — | — |
| Prospekt | 2008 | — | — |
| Protectors | 1 July 2009 | — | — |
| Psapp | 2002 | — | — |
| Psychlona | 2016 | — | — |
| Psython | 2014 | — | — |
| Public Image Ltd | 1978 | — | — |
| Public Service Broadcasting | 2010 | — | British rock four‐piece |