Dr. Ajay Kumar joined the Indian Administrative Service in 1985 and retired as Defence Secretary of India on 31.10.2022. 

He is B. Tech. in Electrical Engineering from the Indian Institute of Technology, Kanpur, India. He is M.S. Applied Economics from the University of Minnesota, USA and Ph.D. in Business Administration from Carlson School of Management, University of Minnesota, USA.

He held various senior level positions in the State Government of Kerala and the Central Government. From July, 2015 to November, 2017, he held the post of Director General, National Informatics Centre (NIC) and Additional Secretary in the Ministry of Communications and IT. He was appointed as the Secretary, Department of Defence Production in the Ministry of Defence in December, 2017 and later as Union Defence Secretary from August, 2019 to October, 2022.

He has spearheaded several initiatives and reforms in his career in the Civil Service. These include corporatization of Ordnance Factories Board, Innovations for Defence Excellence (iDex), AGNIPATH Scheme (Agniveers), promotion of Defence exports in the Ministry of Defence. In the Ministry of Electronics and IT, he was instrumental in revival of electronics system and design industry through a slew of policy initiatives including Modified Special Incentive Package Scheme, Electronic Manufacturing Clusters Scheme, Preference to Domestically Manufactured Goods Scheme, Scheme for setting up semi-conductor fabs, Electronics Development Fund and Compulsory Registration Order mandating safety standards of electronic goods. As DG, NIC he was instrumental in launching various Digital India initiatives including MyGov, Jeevan Pramaan, biometric attendance system among others. While in Kerala, Dr. Ajay Kumar is credited to have revived Kerala State Electronics Development Corporation (KELTRON) during 2000-2002 period and scaling-up of IT investments in the State during his tenure as Secretary IT of the State.

He has, to his credit, several publications in national and international journals including at ICIS, IEEE, IJEC, HICCS etc. He was awarded the "Silver Elephant" medallion by National Scouts and Guides by His Excellency the President of India, in 1994. In the same year, he also earned a citation by the Hon'ble Prime Minister of India and was adjudged the "Outstanding Young Person" by the Junior Chamber of Kerala.
He earned the Graduate School Fellowship by the University of Minnesota, USA for the years 2004 and 2005. He was adjudged as the "Electronics Leader of the Year" for the year 2012 for promotion of electronics industry in the country. He was awarded the Technovation Sarabhai Award by IESA in 2015 for his outstanding contribution to ESDM Industry and was also awarded the “Champion of Change” Award by CEAMA in 2017. He was also awarded Distinguished Alumnus Award (DAA)-2019 of IIT Kanpur. He was conferred Fellowship of the Indian National Academy of Engineering (INAE) for his outstanding contributions to engineering and dynamic leadership in engineering domain which have immensely contributed for the faster development of the country with effect from November 1, 2021.
He has been appointed Chairman, Union Public Service Commission by the Hon’ble President of India on 15th May, 2025.