Objective: The study investigated the prevalence of suicidal behavior and its association with depression, hopelessness, perceived burdensomeness, and thwarted belongingness in a sample of undergraduates in Nigeria. Introduction: Suicide is a leading cause of death among young adults globally. However, information about suicidal ideation, attempts, and relationships with psychiatric factors, perceived burdensomeness, and thwarted belongingness is sparse in Nigeria. The study investigated the prevalence of suicidal ideation and attempts and associated factors in a sample of undergraduates in Nigeria. Methods: We collected data from a cross-sectional survey of 625 undergraduate students primarily recruited from universities, colleges of education, and polytechnics in Adamawa Central Senatorial Zone, Adamawa State, northeast Nigeria. The Suicidal Behaviors Questionnaire-Revised, the 15-item Interpersonal Needs Questionnaire, the 9-item Patient Health Questionnaire, and the 20-item version of the Beck Hopelessness Scale were administered to the participants. We used descriptive statistics and binary and multivariate logistic regressions for data analysis. Results: A total of 616 students with a mean age of 21.41 ± 4.72 years completed the study. The prevalence of suicidal behavior was 34.9% (215/616). Having a female sex (adjusted odds ratio [AOR] = 8.37, 95% confidence interval (CI): 2.06, 34.03), depression (AOR = 45.15, 95% CI: 0.95, 5.11), hopelessness (AOR = 20.10, 95% CI: 5.56, 72.41), and perceived burdensomeness (AOR = 89.15, 95% CI: 29.63, 268.30) were associated with suicidal ideation. In addition, being a female (AOR = 1.69, 95% CI = 1.02, 2.83), being a 200-level student (AOR = 3.41, 95% CI = 1.46, 7.96), and being a 300-level student (AOR = 0.28, 95% CI = 0.11, 0.74) were associated with suicidal attempt. Conclusion: The study’s findings show that suicidal behaviors (ideations and attempts) are prevalent among undergraduate students in northeast Nigeria. The findings underline the need for the development of mental health services and early identification and intervention for at-risk young people in Nigeria.