Background <p>Vasectomy is a safe and effective family planning method; however, research on its acceptance among men in professional occupations remains sparse. This study aimed to assess the awareness, knowledge, and attitudes of secondary school teachers in Southwest Nigeria towards vasectomy, along with their willingness to accept it.</p> Methods <p>A cross-sectional analytical study was conducted among 362 male secondary school teachers using a multistage cluster sampling technique. Data on sociodemographic characteristics, knowledge, attitudes, and willingness to accept vasectomy were collected using a validated structured questionnaire and analyzed using descriptive statistics, chi-square tests, and logistic regression, with statistical significance set at <i>p</i> &lt; 0.05.</p> Results <p>The mean age of the respondents was 41.7 ± 8.2&#xa0;years. While 81.5% were aware of vasectomy as a modern family planning method, 64.9% demonstrated poor knowledge, and 64.6% had negative attitudes. Only 4.7% were willing to accept a vasectomy. Interestingly, a higher proportion of those in polygamous families (15.6%) expressed willingness to undergo the procedure compared to those in monogamous families (3.6%) (<i>p</i> = 0.002). Similarly, individuals with good knowledge showed a higher willingness (7.8%) than those with poor knowledge (2.1%) (<i>p</i> = 0.038). Logistic regression showed that secondary school teachers in polygamous families were four times more likely to be willing to accept vasectomy (OR = 4.31; CI [1.47–12.69]).</p> Conclusion and recommendations <p>Secondary school teachers’ knowledge of vasectomy was low, and negative attitudes were prevalent. Despite the low overall acceptance, willingness was higher among those in polygamous families. Public health interventions should target men, particularly secondary school teachers, to promote vasectomy acceptance through improved knowledge and positive attitude formation.</p>