I
- I.Ae.
- IAME
- IHI
- Imperial
- Industria Aeronautică Română - Romania
- ITP - Spain
- IL
- International
- International Aero Engines (Multinational)
- Irwin
- Isaacson)
- Ishikawajima-Harima Heavy Industries — Japan
- Isotov
- Isotta-Fraschini — Italy
- Italian American Motor Engineering - Italy
- Ivchenko-Progress — Ukraine/Soviet Union
Read more about this topic: List Of Aircraft Engine Manufacturers