| Other Tales Interactive | Denmark | — | 1 | 1 |
| Otomate | Japan | April 10, 2007 | 16 | — |
| Ouat Entertainment | France | 1999 | 4 | — |
| Out of the Blue | Spain | — | 1 | — |
| Out of the Park Developments | Germany | — | 19 | 19 |
| Outerlight | United Kingdom | December 2002 | 1 | — |
| Outerloop Games | United States | — | 1 | — |
| Outfit7 | Slovenia | 2009 | 7 | 1 |
| Outrage Games | United States | 1997 | 1 | — |
| Outright Games | United Kingdom | 2016 | — | 29 |
| Over The Moon | Canada | 2013 | 3 | 2 |
| Over the Top Games | Spain | 2008 | 1 | 1 |
| OverBorder Studio | Taiwan | — | 1 | — |
| Overdose | Japan | — | 1 | 1 |
| Overflow | Japan | 1997 | 4 | 1 |
| OverGamez | Russia | — | — | 4 |
| Overkill Software | Sweden | 2009 | 3 | — |
| Oversight Productions | United Kingdom | August 28, 2019 | 1 | — |
| Oxford Softworks | — | 1989 | 2 | 1 |
| Oxygen Games | United Kingdom | 2004 | — | 5 |
| P2 Entertainment | United Kingdom | December 23, 2004 | 1 | 1 |
| Pack-In-Video | Japan | August 3, 1970 | 3 | 6 |
| Page 44 Studios | United States | 1998 | 1 | — |
| Paintbucket Games | Germany | — | 3 | — |
| Paks | Hungary | — | 1 | — |
| Palace Software | United Kingdom | 1984 | 4 | 1 |
| Paladin Studios | Netherlands | July 2005 | 2 | — |
| Palette | Japan | 2002 | 1 | — |
| Palm Pioneer | People's Republic of China | May 2014 | 1 | — |
| PAM Development | France | 1997 | 2 | — |
| Pan Vision | Sweden | 2001 | 3 | 19 |
| Panasonic Corporation | Japan | 1918 | — | 1 |
| Pandemic Studios | United States | 1998 | 7 | — |
| Pandora Box | Japan | 1989 | 1 | — |
| Pangea Software | United States | 1987 | 3 | 2 |
| Panic | United States | — | — | 5 |
| Panic Barn | United Kingdom | August 2012 | 3 | — |
| Panic Button | United States | 2007 | 2 | — |
| Panther Games | — | 1985 | 2 | — |
| Panther Software | Japan | 1987 | — | 1 |
| Paon DP | Japan | January 20, 1999 | 6 | — |
| Papaya Studio | United States | 1999 | 4 | — |
| Parabole | Canada | 2012 | 1 | — |
| Paradigm Entertainment | United States | March 1997 | 6 | — |
| Paradox Interactive | Sweden | 1999 | 7 | 54 |
| Paradox Tinto | Spain | 2020 | 1 | — |
| Paragon Software | United States | 1987 | — | 1 |
| Parallel Studio | France | October 2015 | 1 | — |
| Paramount Pictures | United States | May 8, 1912 | — | 1 |
| Paranoid Interactive | Poland | — | 1 | — |
| Park Place Productions | United States | 1989 | 3 | — |
| Parker Brothers | United States | 1883 | 1 | 5 |
| PassTech Games | France | October 11, 2012 | 2 | — |
| Pastagames | France | 2001 | 1 | — |
| Pathea Games | People's Republic of China | 2010 | 6 | 1 |
| Pavonis Interactive | United States | 2015 | 1 | 1 |
| Pax Softnica | Japan | May 14, 1987 | 3 | — |
| PBI Software | United States | — | — | 1 |
| Peach Princess | United States | — | — | 10 |
| Pearl GmbH | Germany | September 6, 1989 | — | 1 |
| Pearson Education | Italy | 1998 | 1 | — |
| Pencil | Japan | — | — | 4 |
| Pendulo Studios, S.L. | Spain | 1994 | 4 | — |
| Penguin Pop Games | United States | January 18, 2021 | — | 6 |
| Penguin Software | United States | 1980 | — | 2 |
| PennFilm Studio AB | Sweden | 1967 | 1 | — |
| Pentavision | — | February 3, 2004 | — | 1 |
| People Can Fly | Poland | 2002 | 1 | — |
| Perfect Entertainment | United Kingdom | 1991 | 3 | — |
| Perfectly Paranormal | Norway | August 12, 2015 | 1 | — |
| Persha Studia | Ukraine | 2000 | 1 | — |
| Person of Interests | United Kingdom | January 15, 2021 | 1 | 1 |
| Personal Software Services | United Kingdom | 1981 | — | 2 |
| Perun Creative | Czech Republic | — | 1 | 1 |
| Petit Depotto | Japan | — | 1 | 1 |
| Petit Fabrik | Brazil | 2012 | 2 | — |
| Petite Games | Mexico | — | 7 | 1 |
| Petoons Studio | Spain | 2016 | 5 | 1 |
| Petroglyph Games | United States | April 2003 | 7 | 3 |
| PF Magic | United States | 1991 | 2 | — |
| Phantagram | South Korea | 1994 | 1 | — |
| Phenomedia | Germany | 1999 | 2 | 4 |
| Phigames | United Kingdom | — | 1 | — |
| Philips Interactive Media, Inc. | Netherlands | 1990 | — | 5 |
| PHL Collective | United States | — | 5 | — |
| Phoenix Games Ltd. | Netherlands | May 2002 | 1 | 2 |
| Phoenix Labs | Canada | April 2014 | 1 | 1 |
| Phoenix Studio | France | April 16, 2004 | 1 | — |
| Phoenixx | Japan | — | — | 8 |
| Pi Studios | United States | 2002 | 2 | — |
| Piccolo Studio | Spain | — | 1 | — |
| Picorinne Soft | Japan | — | 2 | — |
| PID Games | France | — | — | 21 |
| PID Publishing | France | 2020 | — | 1 |
| Piece of Cake studios | France | October 26, 2015 | 2 | 1 |
| Piko Interactive | — | 2013 | 6 | — |
| Pikpok | New Zealand | May 1997 | 4 | 2 |
| Pine Studio | Croatia | 2012 | 3 | 3 |
| Pionesoft | Japan | — | — | 1 |
| Pipe studio | Russia | 2002 | 2 | — |