This study examined the COVID-19 vaccine hesitancy rate among undergraduate students in Nigeria. It also investigated differences in COVID-19 hesitancy of undergraduates based on gender, institution type, and academic discipline. A descriptive survey method was employed for the study. The study population comprised undergraduate students in tertiary institutions in Osun State. Three tertiary institutions were selected using a stratified sampling technique; three campuses were selected from a public university which included health and non-health-related courses. In addition, a public polytechnic and a private university were also selected from a total of five campuses. A convenient sampling technique was used to select 500 respondents. The Covid-19 Hesitancy Questionnaire (CHQ) instrument with reliability coefficients of 0.716, 0.872, and 0.834 using Split-half, Cronbach Alpha, and Spearman-Brown, respectively. The study revealed a high rate (81.8%) of COVID-19 hesitancy among Osun State tertiary institutions undergraduate students. Statistically, there was no significant difference in COVID-19 vaccine hesitancy of students based on gender and institution type [t (2,498) =0.65; P > 0.05] and [t (2,498) =0.13; P > 0.05]; whereas, a significant difference was found in the COVID-19 vaccine hesitancy of students based on academic discipline [t (2,498) =0.00; P < 0.05]. It is suggested that government should convey trusted information on the COVID-19 vaccine through the use of different media as well as improving vaccination services. There should be proactive and effective initiatives to fight misinformation regarding the COVID-19 vaccine.