Jiagge was awarded the Grand Medal of Ghana and the Gimbles International Award for Humanitarian Works in 1969. She was named a judge of the Court of Appeal that same year, the highest court in Ghana at the time. She was the first female judge of the Court of Appeal. She was awarded an honorary law degree from the University of Ghana in 1974. In 1975, she founded the Ghana National Council on Women and Development and was its first chair. As chair, she convened a meeting of Ghanaian women to learn their views on Equality, Development and Peace, the theme of the 1975 International Women's Conference in Mexico. She learned that access to credit was a priority for her country's women and led Ghana's delegation to the conference. She and others pledged seed money for a women's bank, and the organisation Stitching to Promote Women's World Banking (now Women's World Banking) was founded and headquartered in New York. She later served on the board of Women's World Banking in Ghana. Jiagge also served as a president of the World Council of Churches from 1975 to 1983. In 1979, she was a member of the constituent assembly which wrote the constitution of the Ghana's Third Republic. She was the World Council of Churches' moderator for their Programme to Combat Racism from 1984 to 1991 and mobilised against South Africa's system of apartheid.