Ji or ji may refer to:

  • Ji (surname) (姬), the surname of the Zhou dynasty
  • Ji (surname) (吉, 己, &c.), other Chinese surnames
  • Ji, variant romanizations of surnames written Chi (e.g., 池) or Zhi (e.g., 智) in pinyin
  • The State of Ji ( 薊國, 蓟国), a city-state in northern China during the Shang and Zhou dynasties
  • Ji (city), the capital of Ji and its successor Yan within modern Beijing, China
  • Ji province:
  • (冀), the character abbreviation for Hebei, China
  • (吉), the character abbreviation for Jilin, China
  • Ji County:
  • Ji County, Shanxi (吉县) in Linfen
  • Ji County, Tianjin (蓟县)
  • -ji, a suffix denoting respect in the Indian subcontinent
  • ji (字), a Japanese courtesy name
  • ji (halberd) (戟), a kind of Chinese halberd
  • ji (flute) (지, 篪), an ancient Korean bamboo flute
  • Ji Koizumi, a character in the anime Guru Guru Pon-chan
  • Ji (magazine), a Ukrainian cultural magazine
  • Ji (film), a Tamil film starring Ajith and Trisha Krishnan
  • Ji (album), an album by English singer Junior Giscombe

JI may refer to:

  • Jemaah Islamiyah, the militant Islamic organization
  • Midway Airlines (JI) IATA code
  • Journal of Infection, an academic journal
  • Joint Implementation, one of the flexible mechanisms of the Kyoto Protocol
  • Journal Inquirer, a Connecticut newspaper
  • Jakobshavn Isbræ, a glacial outlet in Greenland
  • Jurong Institute, a now-defunct pre-university institution in Singapore