Ajay Kumar (born 2 October 1962) is an officer of the Indian Administrative Service, of the batch of 1985. He served as the Defence Secretary of India. He is an alumnus of IIT Kanpur and the University of Minnesota and was awarded separate two fellowships by the University of Minnesota.

Ajay Kumar is known for his in depth knowledge for technology and was instrumental in path breaking policy formations such as electronics manufacturing, mobile manufacturing and also played decision making role in Govt of India’s flagship Digital India program.

He is accredited to scale up defense exports to approximately 13,000 crores with the introduction of modern warfare capabilities and disruptive technologies and innovations. He established the iDEX initiative to help create a conducive and cost-effective defense start-up ecosystem that fosters innovation and technology development. He was in charge of Project 75I, which is developing next-generation submarines and fighters and laying the groundwork for a future marine and aerospace industrial ecosystem in India.

Kumar has a Bachelor of Technology in electrical engineering from the Indian Institute of Technology Kanpur, has a master's degree in development economics from the University of Minnesota, and has a PhD degree in business administration from the Carlson School of Management at the University of Minnesota.

In 2019, he was felicitated as a distinguished alumnus by the Indian Institute of Technology Kanpur for his professional excellence and nation-building efforts

Kumar has served in various posts in both the Government of India and the Government of Kerala, such as Principal Secretary (Information Technology), managing director of the Kerala State Electronics Development Corporation, Secretary (Industries), managing director of the Kerala State Co-operative Agricultural and Rural Development Bank, general manager in the Kerala State Industrial Development Corporation and as the district magistrate and collector of the Palghat (now Palakkad) district in the Kerala government; and as the Defence Production Secretary, additional secretary in the Ministry of Electronics and Information Technology, joint secretary in the Department of Information Technology of the now-erstwhile Ministry of Communications and Information Technology, director in the Department of Biotechnology of the Ministry of Science and Technology and as a deputy secretary in the Department of Home of the Ministry of Home Affairs in the Indian government.

Ajay kumar spent three decade of his service with the Kerala state government where he headed three different departments.

Kumar also served as a private secretary to a minister in the Ministry of Non-Conventional Energy Sources (now Ministry of New and Renewable Energy).

Principal Secretary

He was Principal Secretary to Government of Kerala, Information Technology Department from October 2007 to December 2010.

Joint Secretary

Kumar held the post of Joint Secretary, Ministry of Electronics and Information Technology and additional charge of Director General at National Informatics Centre from 2010 to 2014.

Additional Secretary

He was Additional Secretary, Ministry of Electronics and Information Technology during 2015 - 2019

Defence Production Secretary

Kumar was appointed as the Defence Production Secretary by the prime minister-headed Appointments Committee of the Cabinet in November 2017, he assumed office on 1 December 2017. He served as Defence Production Secretary till 23 August 2019 and was succeeded by Subhash Chandra, an IAS officer of Karnataka cadre (1986 batch).