IOI may refer to:
Arts and entertainment
- Interonset interval, in music
- I.O.I, a South Korean girl group formed from the television show Produce 101
- Innovative Online Industries (IOI), a fictional corporation in the 2011 novel Ready Player One
- Ready Player One (film), the 2018 film adaptation
Organisations
- International Ombudsman Institute, global organisation
- IOI Group, a Malaysian conglomerate
- IO Interactive, a Danish video game developer
Science and technology
- Idiopathic orbital inflammatory disease, involving any area of the orbit
- International Olympiad in Informatics, an annual competitive programming competition
Other uses
- Indication of interest, in financial trading
- Interest on investment or return on investment
- Island of Ireland, the geographical entity encompassing both the Republic of Ireland and Northern Ireland
See also
- LOL (disambiguation)
- 101 (disambiguation)