I
- IAC (1), International Aeromarine Corporation – United States, (1982–?)
- IAC (2), International Aviation Corporation – United States, (1982–?)
- IAD, International Aircraft Deliveries – United States, (1962–1965)
- IAI, Israel Aerospace Industries Ltd – Israel
- IAI, Israel Aircraft Industries Ltd – Israel
- Iannotta, Dott. Ing. Orlando Iannotta – Italy
- IAR, IAR (Industria Aeronautică Română) SA – Romania
- Iberavia, Spain
- IBIS, Ibis Aerospace Ltd – Czech Republic/Taiwan
- Ibis Aircraft, Ibis Aircraft S.A., Cali, Colombia
- ICA, Intreprinderea de Constructii Aeronautice – Romania
- ID Integration, ID Integration, Inc. – United States
- Ikar, OOO Aviaklub Ikar – Ukraine
- Ikarus, Ikarus Tvornica Aero i Hydroplana – Serbia and Montenegro
- Ilyushin, Aviatsionnyi Kompleks Imeni S. V. Ilyushina OAO – Russia
- Ilyushin, Ilyushin OKB – Russia
- Ilyushin – see Aviation Association Ilyushin
- IMAM, Industrie Meccaniche e Aeronautiche Meridionali – Italy
- IMCO, Intermountain Manufacturing Company – United States, (1962–1966) > Rockwell
- IMP, IMP Group Ltd – Canada
- Impulse, Impulse Aircraft GmbH – Germany
- Indaer Chile, Industria Aeronáutica de Chile – Chile
- Indaer Peru, Industria Aeronautica del Peru SA – Peru
- Independence Paragliding, (A brand of Fly-market Flugsport-Zubehör GmbH & Co. KG) Eisenberg, Germany
- IAe, Bandung – Indonesia
- Indus, IndUS Aviation Inc – United States
- Indy Aircraft Limited, Independence, Iowa, United States
- Industrias Aeronauticas y Mecanicas, Industria Aeronáutica y Mecánica del Estado (IAME) – Argentina, (1953–1957) (Aeronautical and Mechanical Industries of the State) > DINFIA
- Infinity Power Chutes, Sturgis, Michigan, United States
- Iniziative Industriali Italiane, Iniziative Industriali Italiane – Italy
- Innovation, Innovation Engineering Inc – United States
- INPAER - Brazil
- Instituo Aerotecnico, Instituto Aerotécnica (Fabrica Militar de Aviones) – Argentina, (1943–1957) (IA) > DINFIA
- Instytut Lotnictwa, Instytut Lotnictwa – Poland
- Inter-Air, International Aircraft Manufacturing Inc – United States, (?-1967) > Bellanca
- Interavia, Interavia Konstruktorskoye Buro AO – Russia
- Interceptor Corporation, Interceptor Corporation – United States
- International Helicopters, International Helicopters Inc – United States
- InterPlane Aircraft, Zbraslavice, Czech Republic
- Interstate Engineering Corporation|Interstate, Interstate Engineering Corporation – United States
- Intracom, Intracom General Machinery SA – Switzerland
- IPAI, IPAI, Escola de Engenharia de Sâo Carlos – Brazil
- IPT, Instituto de Pesquisas Tecnologicas – Brazil
- IPTN, PT. Industri Pesawat Terbang Nusantara – Indonesia
- IRGC, Institute of Industrial Research and Development of the Iran Revolutionary Guard Corps – Iran
- IRIAF, Islamic Republic of Iran Air Force – Iran
- Irkut, Irkutskoye Aviatsionnoye Proizvodstvennoye Obedinenie OAO – Russia
- IRMA, Intreprinderea de Reparat Material Aeronautic – Romania
- Isaacs, John O. Isaacs – United Kingdom
- ISAE, Integrated Systems Aero Engineering Inc – United States
- Island Aircraft, Island Aircraft Ltd – United Kingdom
- Israviation, Israviation Ltd – Israel
- Issoire, Issoire Aviation SA – France
- ITV Parapentes, Épagny, Haute-Savoie, France
- Ivanov Aero, Hradec Králové, Czech Republic