INTRODUCTION: COVID-19 vaccine hesitancy is a worldwide phenomenon and a serious threat to pandemic control efforts. Until recently, COVID-19 vaccine hesitancy was not the cause of low vaccine coverage in Nigeria; vaccine scarcity was the problem. As the global supply of COVID-19 vaccines improves in the second half of 2021 and more doses are deployed in Nigeria, the supply/demand dynamic will switch. Vaccine acceptance will become a key driver of coverage; thus, amplifying the impact of vaccine hesitancy. Conspiracy theories and misinformation about COVID-19 are rampant and have been shown to drive vaccine hesitancy and refusal. This study systematically elicits the misinformation and conspiracy theories circulating about COVID-19 among the Nigerian public to understand relevant themes and potential message framing for communication efforts to improve vaccine uptake. METHODS: From February 1 to 8, 2021, we conducted 22 focus group discussions and 24 key informant interviews with 178 participants from six states representing the six geopolitical zones. Participants were purposively selected and included sub-national program managers, healthcare workers, and community members. All interviews were iteratively analyzed using a framework analysis approach. RESULTS: We elicited a total of 33 different conspiracy theories or misinformation that participants had heard about the COVID-19 virus, pandemic response, or vaccine. All participants had heard some misinformation. The leading claim was that COVID-19 was not real, and politicians took advantage of the situation and misused funds. People believed certain claims based on distrust of government, their understanding of Christian scripture, or their lack of personal experience with COVID-19. CONCLUSIONS: Our study is the first to report a thematic analysis of the range of circulating misinformation about COVID-19 in Nigeria. Our findings provide new insights into why people believe these theories, which could help the immunization program improve demand generation communication for COVID-19 vaccines by targeting unsubstantiated claims.