Shehu was educated at Kaduna College from 1941 to 1944. After teacher training at Zaria from 1944 to 1945 he became a science master in Sokoto Middle School from 1945 to 1950 and headmaster at Argungu School from 1951 to 1954. After further teacher training courses in Bauchi and Britain he became senior visiting teacher in Sokoto province.
He was one of the few young men with education keen to form a political party. They founded a cultural organisation in 1949 which eventually became the NPC in 1951. In 1954 he stood for the Sokoto West constituency and was returned unopposed.
In 1958 he was made the Parliamentary Secretary to the Prime Minister, Sir Abubakar Tafawa Balewa who encouraged him in his political career and made him Minister for Economic Development in 1960 for a brief spell before shuffling him to Federal Minister of Establishments from 1960 to 1962. He continued to hold successive ministerial appointment's through every Balewa cabinet, as Minister of Internal Affairs, 1962-5; Minister of Works until the military coup in January 1966. By then he was the fourth most senior minister in the Balewa cabinet.
He escaped being killed and as the Premier had vanished helped try to form a new government, but power was taken over almost immediately by General Ironsi and he retired to his farm in Shagari. Soon he was back in voluntary public service as Secretary of the Sokoto Province Education Development Fund, being appointed Director of the Northern States Marketing Board in 1968.
He continued to serve in the Northwestern State, becoming Commissioner for Establishments in August 1968 and Commissioner for Education in 1969. General Gowon noted his professionalism and quiet industry and brought him back to Lagos as Federal Commissioner for Economic Development, shuffling him to take over the important finance portfolio from Chief Awolowo on October 20, 1971.
A Fulani teacher, with a gentle manner and diffident smile behind gold-rimmed glasses, he was leader among the first generation to take to politics in the North. A founder member of the Nor-thern Peoples' Congress, he was closely connected with the later Premier Sir Abubakar Tafawa Balewa serving in four ministries over an unbroken span of six years under him. He became an ideal civil servants’ minister, reliable, impartial and clear headed. After the Nigerian coup he went quietly back to his farm and soon started again in state public service, to be brought back later by General Gowon as one of his commissioners.
After, becoming the science teacher for Sokoto Middle School, he had a close look at arranged marriages. His uncle Magaji Basharu and his brother, Bello had tried to have him marry Basharu's granddaughter. However, Shagari gave the visiting bridal train a taunting look. After the visitors left and in the tense atmosphere, the bride followed them briskly. Shagari later married twice to Hadiza and Aishatu Shagari.