The dramatic deepening of Nigeria's economic relationship with China between 2015 and 2024 has generated fundamental questions about its implications for Nigerian foreign policy independence and sovereign decision-making capacity. Under the Buhari administration (2015–2023), Nigeria contracted approximately $5.5 billion in infrastructure loans from Chinese financial institutions, transforming China into Nigeria's largest bilateral creditor and raising important questions about the nature and implications of the bilateral economic engagement. Drawing on Dependency Theory, Neorealism, and the concept of African Agency, and deploying a mixed methods approach combining qualitative content analysis of loan agreement texts with quantitative Voting Coincidence Index analysis of Nigeria's United Nations General Assembly voting records, this article critically examines whether Nigeria's relationship with China constitutes a genuine strategic partnership of equals or a structurally asymmetric dependency relationship that compromises Nigerian foreign policy independence. The analysis reveals that Nigeria–China loan agreements contain consistent patterns of sovereignty-constraining conditionalities including contractor nationality clauses, sovereign immunity waivers, and asymmetric dispute resolution mechanisms that structurally favor Chinese interests. The Voting Coincidence Index analysis reveals a temporal correlation between Nigeria's Chinese debt exposure and its UNGA voting alignment with China, with the overall VCI rising from 72 percent in 2015 to a peak of 83 percent in 2021 before declining modestly to 70 percent under the Tinubu administration (2023–2024). The article concludes that Nigeria's relationship with China is best characterized as a structurally asymmetric partnership in which Nigeria participates with genuine but unequal agency under conditions that create significant structural pressures on its foreign policy autonomy without entirely eliminating its capacity for independent sovereign action. The article contributes to the theoretical literature by demonstrating the continued relevance of Dependency Theory as a framework for understanding structurally asymmetric South–South economic relations in the twenty-first century.