IMO or Imo may refer to:
Maritime International Maritime Organization IMO number, a unique identity number issued to seacraft (pattern "1234567") SS Imo, a 1889 ship involved in the Halifax Explosion
Meteorology International Meteorological Organization Icelandic Meteorological Office
Other Irish Medical Organisation Intelligent Medical Objects, a privately held company specializing in medical vocabularies Isomaltooligosaccharide, a mixture of short-chain carbohydrates which has a digestion-resistant property Idiopathic Massive Osteolysis, a name for Gorham's disease, a rare bone disease International Mathematical Olympiad International Meteor Organization Imo State, Nigeria imo.im, a video calling and instant messaging app IMO (in my opinion), an Internet slang expression