PJ may refer to:
- The PJ or The Pharmaceutical Journal, a publication of the Royal Pharmaceutical Society of Great Britain
- P.J. (film), a 1968 film starring George Peppard
- PJ Media
- PJ Trailers, an American trailer manufacturer
- Petajoule
- Picojoule
- Pajamas or PJs
- Parajumpers, Air Force Pararescue operatives of the US Air Force
- Partido Justicialista, a major Argentine political party
- Peace Journalism, a journalistic technique that corrects for value bias in favour of violent responses to conflict
- Peach John, a Japanese lingerie retailer a who use "pj" as their logo
- Pearl Jam, American rock band
- Petaling Jaya, a Malaysian city
- Polícia Judiciária, Portuguese criminal investigation police
- Air Saint-Pierre's IATA code
Read more about PJ: People Known By The Initials