Jo, jo, JO, or J.O. may refer to:
- JO, ISO country code for Jordan
- JO, IATA code for JALways, an airline that is a subsidiary of Japan Airlines
- JO, the U.S. Navy rating abbreviation for "journalist"
- .jo, the internet country code top-level domain (ccTLD) for the country of Jordan
- Journal Officiel de la République Française, the official gazette of the Government of France
- Les Jeux Olympiques, French for Olympic Games
- Jo (given name)
- Jō (surname), a Japanese surname
- Cho (Korean name), a common Korean surname which can be romanized as "Jo"
- jō (杖), a wooden staff used in some Japanese martial arts, about 4 Japanese feet long
- jō (丈), a Japanese unit of length equivalent to the Chinese zhang, equal to 10 Japanese feet
- jō (畳), a Japanese unit of area corresponding to the area of a standard tatami mat (1×½ ken or 18 square Japanese feet)