Background: In the era of HIV treatment as prevention, little research has focused on the fertility behaviour of men living with HIV. This study examines the predictors and motivators of fertility among men living with HIV and on antiretroviral treatment in Kano, Nigeria. Method: Using mixed methods, structured questionnaires were administered to a clinic-based sample of men living with HIV (n = 270) and HIV-negative/untested controls (n = 270), followed by in-depth interviews with a sub-group of 22 HIV-positive participants. Logistic regression and the framework approach were used to analyse the data. Results: Compared to HIV-negative/untested controls, lower proportions of men living with HIV desired more children (79.3%, n = 214 vs. 91.1%, n = 246, p < 0.05) and intended to bear children within 3 years (57.0%, n = 154 vs. 67.0%, n = 181) (p < 0.05). Marital status (ever married vs. single) predicted fertility intention among men living with HIV (adjusted odds ratio, AOR = 4.70, 95% confidence interval CI, 1.75–13.64) and HIV-negative/untested controls (AOR = 4.23, 95% CI, 1.37–16.45). Men considered self and partner health status, HIV transmission risks, poverty, the effectiveness of interventions, child survival and religion when making fertility decisions. Conclusion: Fertility desires remain high post-HIV diagnosis. HIV services should include integrated reproductive health programs that address the fertility desires of clients and include considerations for fertility services.