Anyone born or raised in Nigeria, Africa's most populous country, after 1960 would remember Children's Day, observed every 27 May. However, few knew that it started as Empire Day in the first decade of the twentieth centuryfewer are aware that it was a significant symbol of imperial domination, decolonised from the late 1950s to align with postcolonial ideals of self-determination and nation-building. African historical research has examined the sites and symbols (such as western biomedicine and education, police and prison, and indirect rule) through which British imperialism established and maintained itself in Africa. However, little is known about Empire Day, an invented tradition of ritualistic yearly veneration of the glory of the British Empire, which was first celebrated in Britain in 1904 and was immediately introduced to the African colonies. In this article, I examine the story of Empire Day as a significant colonial spectacle and performance of imperial authority in Nigeria, and how it assumed new meanings and functions among diverse groups of Nigerian children and adults. Empire Day, more than any other commemoration, placed children at the centre of imperialism and recognised them as a vital element in the sustenance of an imagined citizenship of the British Empire.