J2K may refer to:

  • JPEG 2000, the image compression standard
  • J2K-Codec, a proprietary library to decode JPEG 2000 images
  • The US Coast Guard designation for the Fairchild 24 light transport aircraft
  • Josh Young, former member of Flosstradamus, a musical duo
  • Jason Black, member of Roll Deep, an English grime (music) crew