P239 may refer to:

  • HMS Peacock (P239), now known as BRP Emilio Jacinto (PS-35), a corvette formerly of the Royal Navy which now serves in the Philippine Navy
  • HMS Surf (P239), a submarine of the Royal Navy that served during World War II
  • The SIG Sauer P239, a compact semi-automatic pistol
  • An isotope of Plutonium. Used in nuclear weapons.