The Prime minister was the head of government in the country from 1960 to 1966, when the office was replaced by the president of Nigeria holding this role.
When Nigeria gained independence from the United Kingdom on 1 October 1960, it originally had a parliamentary constitutional monarchy with Queen Elizabeth II as the head of state.
But in 1963, Nigeria ended its status as a Commonwealth Realm and became a republic.
[1] The head of state was the president, while the prime minister served as the head of government.
In 1966, the office of prime minister was abolished (as the inaugural holder of the office, Abubakar Tafawa Balewa, had been assassinated) and since then, Nigeria has been a presidential republic with the president as the head of state and head of government.