IARI has pioneered rural development and extension of new agricultural technologies to the farmers since 1950s. With the objective of carrying the findings of research to the villages for the improvement of agriculture and efficient utilization of resources, the Institute launched a pioneering pilot scheme of 'Intensive Cultivation' in 19 villages of the Union Territory of Delhi. It was planned to gradually saturate the villages with improved varieties of major crops while emphasizing proper land utilization. An Extension Center at Nangloi was established in 1955 on a patch of one acre land taken on lease from the Municipal Corporation of Delhi. In the wake of the 'Intensive Cultivation Scheme', various measures were taken to educate the farmers in the use of improved agricultural methods. Among these, the setting up of an Agricultural Museum was one of its important features.
The extension activities of the Institute assumed a great significance by the end of the decade (1950- 59) of extension activity in the 19 villages of Delhi. The extension activities were strengthened in 1955-56 under the Second Five Year Plan, when students began to be admitted for the post-graduate training in Agricultural Extension leading to the diploma of Associateship, and subsequently to the M.Sc. and Ph.D. degrees of the Institute. Later on, considering the importance of extension education, the necessity of a fledgelings Division of Agricultural Extension was realized. Accordingly, the Government of India eventually sanctioned the establishment of a separate Division of Agricultural Extension at the Institute as a scheme under the Third Five Year Plan. However, the implementation of this scheme was advanced to the Second Five Year Plan itself.

In 1984, the activities of the Division were reorganized and field extension activities were assigned to Centre of Agricultural Technology Assessment and Transfer (CATAT), CATAT is implementing outreach extension programmes of the Institute in Delhi, Haryana Rajasthan and western Uttar Pradesh through various programmes such as Technology Assessment and Refinement (TAR) through Institute Village Linkage Programme (IVLP), Frontline Demonstrations (FLDs), TOT programme, exhibition and advisory services. The Agricultural Technology Information Centre CATIC) is working as a 'Single Window Delivery System' to provide IARI products, services and technologies to the visiting farmers/entrepreneurs. Facilities like 'Plant Clinic' to facilitate immediate diagnosis of plant diseases and pests, information museum giving a glimpse of technology developed by the Institute have been developed at the Centre.

Krishi Vigyan Kendra CKVK), Shikohpur, Gurgaon was established in the year 1984 to further the field extension activities in regions outside of Delhi. This KVK played a vital role in providing linkage with the farmers, farm women and rural youth. In the recent years, it has been playing an important role in combating unemployment of rural youth through technological empowerment and improving the farmers' awareness and farm productivity through various TOT programmes. For speedy dissemination of technologies on the farmers' fields, the KVK organizes various extension activities in the villages and at K'/K campus. The Krishi Vigyan Patrika, a quarterly newsletter in Hindi provides latest and newer technologies to the farmers at proper time to the farmers.
With the changing times, the extension work at IARI was modified to meet the emerging challenges. During the 1960s, the focus of agricultural extension was on adoption of improved technology and effectiveness of extension methods. During the seventies, the emphasis shifted to communication behaviour of farmers and extension personnel, mass media, training needs and development strategies. In the eighties, the emphasis further shifted to technological change, yield gap and constraints analysis, development organizations, extension strategies for mobilizing farmers, impact of T & V system, and extension and research management. The research coverage, thus, moved from micro-level evidences to macro-issues relevant to the national planning. In the early nineties, the various units of extension concentrated on integration of research, extension and client systems, media development, extension management, indigenous farmers' knowledge system, role of farm women and participatory extension approaches. This was followed by researches during 2000 in areas like empowerment, management training modules for interact group, methodologies and sustainable livelihoods.

The Institute constituted an Extension Council in the year 1967, which is a decision making body for the purpose of assessment and execution of extension programmes. The Council works under the chairmanship of the Director, IARI and meets twice a year before the Rabi and Kharif season sowings. The funding sources for extension education and field extension comprise grants from the Institute and additional grants from NATP, Ministry of Agriculture, Govt. of India, ICAR, DST, etc. As per the mandate of ICAR, every scientist is required to devote 20% of his time on extension related activities.