In 1960, he completed the course and that same year returned to be assigned a role in athletic coaching and scouting as Western Regional Sports Organiser. He trained the Ghanaian team for the 1965 All-Africa Games in Congo-Brazzaville where his athletes Rose Hart and Alice Annum won medals. In 1966, he was appointed National Athletic Coach and made acting Chief Administrative Officer of the  Central Organisation of Sports. The Central Organisation of Sports changed to be known as the National Sports Council soon after this. He was selected thrice to be Chief Coach of an All African select contingent to compete in athletics against the United States in 1971,1973 and 1975. Some of his athletics talents unearthed include Mike Ahey, Stan Allotey, BK Mends, Alice Annum and Joshua Owusu. In 1974, Adjin-Tettey drew up and executed a programme for the University of Ghana to host the first All-Africa Inter-University Games. Adjin-Tettey also acted as Sports Consultant to the Ghana Police Service beginning in 1975 and helped the Service host the Security Services Sports Association (SESSA) Games. In 1984, he was removed as an official of the National Sports Council on events connected to the 1984 Los Angeles Olympics. That same year he was a co-foundation member and the first Chairman of the Dansoman Keep-Fit Club which is known for being the organiser of the Accra Milo Marathon since 1987.