[2] Prior to his ambassadorial appointments Amonoo served as principal Secretary to various ministries between 1963 and 1967.
[4] After his tertiary education, Amonoo entered the Gold Coast Administrative Service in 1952.
[4][5] A year later, he became the first Secretary to the Ghanaian permanent mission to the United Nations.
He served in this capacity until 28 September 1968, when he was appointed Ghana's ambassador to Ethiopia.
[4][7] On 18 July 1972, he was appointed Ghana's Ambassador to the United States of America, succeeding Johnson Kwaku Appiah who had served as Ghana's Chargé d'affaires to the United States of America from 2 July 1972, when his ambassadorial duties in Ethiopia came to end, until 18 July 1972, when he was appointed Ghana's ambassador to the United States of America.