Garba first came to national attention in Nigeria when, on 29 July 1975, he announced the coup d'état against the leader of the country, General Yakubu Gowon.

[1] Garba's speech, broadcast from Radio Nigeria, began with the following statement: Fellow countrymen and women, I, Colonel Joseph Nanven Garba, in consultation with my colleagues, do hereby declare that in view of what has been happening in our country in the past few months, the Nigerian Armed Forces decided to effect a change of the leadership of the Federal Military Government.

As from now, General Yakubu Gowon ceases to be head of the Federal Military Government and Commander-in-Chief of the Armed Forces of Nigeria.

In 1975 he was appointed Nigeria's foreign minister (Federal Commissioner for External Affairs) by Murtala Mohammed, and continued in this role under Olusẹgun Ọbasanjọ after the former was assassinated in 1976.

[6] In 1978, as Ọbasanjọ was preparing to hand rule of Nigeria over to civilians, Garba was reassigned to the role of Commandant of the Nigerian Defence Academy.

[6] Returning to diplomatic life, Garba was appointed a Permanent Representative to the United Nations in 1984, a role he continued in until 1989.

[7] Garba remained president for the sixteenth, seventeenth, and eighteenth special sessions of the assembly, on Apartheid, drug abuse, and international economic co-operation respectively.

From 1999, he was Director General of the National Institute for Policy and Strategic Studies in Nigeria, and while carrying out the duties of this office in Abuja he died on 1 June 2002.