Boss Mustapha was born in the North Eastern Nigerian state of Adamawa. He attended primary school in Hong, Adamawa and proceeded to North East College of Arts and Sciences in Maiduguri, Borno State for his high school education. He graduated in 1976.
He received his Bachelor of Law (LL.B) in 1979 from the prestigious Ahmadu Bello University Zaria, and graduated from Nigeria Law School, Lagos in 1980, and was called to Nigerian bar in the same year.
He started his legal practice in Messrs Onagoruwa & Co in Lagos as a Counsel in 1983. He had a stint at an Italian consultancy firm Sotesa Nigeria Limited earlier.
In 1994 he established his own law practice firm Messrs Mustapha & Associates and served as its Principal Counsel until 2000. He later worked in another law firm Adriot Lex & Co. serving as Principal Consultant from 2000 to 2006.
Mustapha has been elected and appointed member of several boards of companies in the manufacturing, financial services and oil and gas sectors both in Nigeria and international scene.
He is a member of several professional bodies including Commonwealth Lawyers Association, African Bar Association, International Bar Association and Human Rights Institute. He has been described by many media reports as a "boardroam guru".
He ventured into politics in the 1980s after law graduation. Between 1988 and 1989 he was a member of the Federal Republic of Nigeria Constituent Assembly, the body that drafted the Nigeria's 1989 constitution. The constitution was only partially used in running the Nigeria's third republic between 1993 and 1999.
In 1989 Mustapha was the state chairman of the Peoples Solidarity Party (PSP) in defunct Gongola State but the party was among the several political parties disbanded by Babangida because they failed government's “litmus test”.
Between 1990 and 1991 Mustapha was Adamawa state chairman of the Social Democratic Party, one of the two state-created political parties during Ibrahim Babangida's regime. He ran unsuccessfully for Adamawa State governorship in 1991 under the party but lost to Abubakar Saleh Michika of National Republican Convention.
He was among the 7-man committee tasked by President Obasanjo to probe Muhammadu Buhari-led Petroleum Trust Fund in 2000.
He served as the deputy director-general of the campaign organisation of Atiku Abubakar's failed presidential bid in 2007 general elections.
He was deputy national chairman of the Action Congress of Nigeria. The party was among the 3 major parties that were merged to form the All Progressives Congress on 6 February 2013 in anticipation of the Nigeria's 2015 general elections.
After merger of their party he served in the presidential campaigns and was among the members of its transition committee in Nigeria's 2015 election that brought Muhammadu Buhari into power. He is also a member of the board of trustees of the party.
Mustapha ran unsuccessfully for Adamawa State governorship in 2014
He was appointed Secretary to the Government of the Federation on 30 October 2017 following sack of Babachir David Lawal who has been on suspension six months earlier for misappropriating public funds.
He took oath of office on 1 November 2017 during a meeting of the Federal Executive Council, in the Council Chambers, Presidential Villa, Abuja.
