In 1894 Lugard visited West Africa for the first time. Employed by the Royal Niger Company, he led an expedition to forestall a French effort to establish a position on the lower Niger River. After a brief tour to Bechuanaland for the British West Charterland Company, he returned to the Niger in 1897 as commissioner for the hinterland of Nigeria and commander of the West African Frontier Force, a military contingent designed to aid the Royal Niger Company in defending its territorial claims.
When the charter of the Royal Niger Company was revoked in 1900, the British government assumed administrative responsibility for former territories of the company, and Lugard became high commissioner for Northern Nigeria. At that time, Northern Nigeria existed in name only, since the company had never extended any form of administration beyond the banks of the Niger. During his tenure Lugard laid the foundations of British rule in the North, first establishing British sovereignty by conquest of the Moslem states which had resisted alien domination and then by developing the forms of administration whereby the British would rule.
In 1906 Lugard resigned as high commissioner and the following year accepted an appointment as governor of Hong Kong, where he remained until 1911. Then, in 1912, he returned to Nigeria as governor of both the Northern and Southern protectorates, charged with amalgamating the two territories into a single unit.
Lugard's plans for amalgamation provided for the extension into the Southern Protectorate of the policy of indirect rule which he had developed in the North. Indirect rule was designed to allow for the administration of colonized peoples through the agency of indigenous institutions. Although indirect rule was not uniformly effective among peoples of very diverse traditional institutions, Lugard pushed hard for its adoption and as a guide published his Political Memoranda, earlier directives he had circulated in establishing the Northern administration. By 1919, when Lugard retired as governor general, Nigeria had been set well on its way to becoming a unified territory administratively.
Upon his return to England, Lugard set to work on his second book, The Dual Mandate in British Tropical Africa (1922). In this book he set out in detail his conceptions of indirect rule and expressed his belief that Britain as an imperial power was responsible for aiding in the social, political, and economic development of its African dependencies. The book was hailed as an authoritative statement of British policy and became a guide to the administration of British dependencies.
Lugard never resumed his service abroad but remained an active public figure until his death in 1945. He was appointed to the Privy Council in 1920 and was a member of the Permanent Mandates Commission of the League of Nations from 1922 to 1936; he also served on several other national and international commissions dealing with Africa. In 1928 he was raised to the peerage. His wife, the former Flora Shaw, was the author of A Tropical Dependency, a history of Nigeria.