IIO

IIO or Iio may refer to:


 * iiO, an American dance music group
 * Iio (surname), in Japan
 * Imperial Inspectorate Organization, or its successor the Islamic Inspectorate Organization in Iran
 * Independent Investigations Office, a police oversight agency in British Columbia, Canada
 * Italian Instabile Orchestra, an experimental big band
 * Information Integration Officers, of the U.S. Air Force; see Aircrew Badge
 * Diminished supertonic triad (iio), a borrowed chord
 * Linux Industrial I/O subsystem