Nii Amoo Darku was born into a muslim family in Ghana, West Africa. He became a practicing muslim when he was twelve. Nii would pray five times a day, go through the month of Ramadan fasting and stayed faithful until 1969. While at high school he was introduced to Christ through "Scripture Union". After only a year he lost faith in Christianity.

In 1970 Nii was again challenged through a Christian television program to rededicate his life to Christ.

After his conversion he became a Presbyterian and helped with a major outreach to the city of Kemai. In 1980 he left his secular employment to become Director of Evangelism of the Ghana Evangelism Committee (GEC). Two years later Nii was called to serve a missionary organization before he stepped out by faith as a freelance evangelist for nearly seven years. During that period, on two different occasions he served as National Coordinator for two major congresses on evangelization in Ghana and also served with the Billy Graham Evangelistic Association as part of Dr. Graham's Global satellite ministry. Nii also co-translated Dr. Graham's sermons into some of his countries local languages.

In 1989 Nii became a full time evangelist for the Grace Baptist church, for seven years during which time, the Church congregation grew from 500 to over 4,000 and 14 daughter churches were planted. In 1995 he responded to a call to serve as national Team Leader with African Enterprise and in October of 1999 was also appointed Deputy International Team Leader for West Africa.