Jayakumar is well known for his 30-year involvement with World Vision. He was National Director for World Vision India for eleven years, before becoming World Vision's global Partnership Leader for Faith and Development from 2015 to 2017. He is the author of the book God of the Empty-handed and many articles related to poverty, urban missions, powerlessness, leadership and integrity. He has also taught in a number of theological seminaries. Jayakumar and his wife Vidhya are based in Chennai (India) and worship in Emmanuel Methodist Church.