Reddy has been a researcher, teacher, policy enabler, advocate and activist who has worked to promote cardiovascular health, tobacco control, appropriate nutrition across the life course, chronic disease prevention and healthy living across the lifespan.

He chaired the High Level Expert Group on Universal Health Coverage, set up by the Planning Commission of India.

He has also served as the President of the National Board of Examinations which deals with post-graduate medical education in India.

Since 2022, Reddy has been a member of the Commission for Universal Health convened by Chatham House and co-chaired by Helen Clark and Jakaya Kikwete.

They include: WHO Director General's Award for Outstanding Global Leadership in Tobacco Control (World Health Assembly, 2003), Padma Bhushan (Presidential Honour, India, 2005), Queen Elizabeth Medal (Royal Society for Health Promotion, UK, 2005), Luther Terry Medal for Leadership in Tobacco Control (American Cancer Society, 2009), Membership of the US National Academies (Institute of Medicine, 2005), Fellowship of the London School of Hygiene and Tropical Medicine (2009), Fellowship of the Faculty of Public Health, UK (2009).