I
- IAAI: International Airport Authority of India
- IAAS: Indian Audit and Accounts Service
- IADF: International Agricultural Development Fund
- IAEA: International Atomic Energy Agency
- IAF: Indian Air Force
- IAMC: Indian Army Medical Corps
- IAS: Indian Administrative Service
- IATA: International Air Transport Association
- IATT: Inland Air Travel Tax
- IBRD: International Bank for Reconstruction and Development
- IBEX: Interstellar Boundary Explorer Mission
- ICANN: Internet Corporation for Assigned Names and Numbers
- ICAO: International Civil Aviation Organisation
- ICAR: Indian Council of Agricultural Research
- ICCR: Indian Council of Cultural Relations
- ICCW: Indian Council for Child Welfare
- ICDS: Integrated Child Development Service
- ICMR: Indian Council of Medical Research
- ICL: Indian Cricket League
- ICRC: International Committee of the Red Cross
- IDA: International Development Association
- IDBI: Industrial Development Bank of India
- IDSA: Institute of Defence Studies and Analysis
- IEA: International Energy Agency
- IES: Indian Economic Service
- IEX: Indian Energy Exchange
- IFRS: International Financial Reporting Standard
- IIT: Indian Institutes of Technology
- ILO: International Labour Organisation
- IMA: Indian Military Academy
- IMF: International Monetary Fund
- IMO: International Maritime Organisation
- IN: Indian Navy; Intelligent Network
- INA: Indian National Army
- INMARSAT: International Maritime Satellite Organisation
- INMAS: Institute of Nuclear Medicines and Allied Sciences
- INS: Indian Naval Ship; Indian Newspaper Society
- INSAS: Indian Small Arms System
- INSAT: Indian National Satellite
- INTERPOL: International Police Organisation
- INTUC: Indian National Trade Union Congress
- IOC: International Olympic Committee
- IP: Indian Police
- IPC: Indian Penal Code
- IPCC: Intergovernmental Panel on Climate Change
- IPR: Intellectual Property Right
- IPS: Indian Police Service; Indian Postal Service
- IPTV: Internet Protocol Television
- IPU: Inter-Parliamentary Union
- IR: Infra-red
- ISH: Information Super Highway
- ISD: International Subscriber Dialled (telephone)
- ISKCON: International Society for Krishna Consciousness
- ISO: International Standardisation Organisation
- ISP: Internet Service Provider
- ISRO: Indian Space Research Organisation
- ISS: International Space Station
- IST: Indian Standard Time
- IRA: Insurance Regulatory Authority
- IST: Indian Standard Time
- ISTRAC: ISRO Telemetry, Tracking and Command Network
- ITDC: Indian Tourism Development Corporation
- ITO: International Trade Organisation; Income-tax Officer
- ITU: International Tele-communication Union
- IUC: Interconnect User Charge