Past findings on the association between negative body image and sexual health behaviors have been mixed and mostly derived from Western samples. The aim of the current study was to examine associations between indices of negative body image and sexual health practices that reduce the risk of disease transmission in emerging adults, and whether these associations are moderated by gender. Using an online survey, a convenience sample of 584 Malaysian adults aged 18-30 years (230 men, 354 women) completed measures of satisfaction with overall appearance, body size dissatisfaction, weight satisfaction, height satisfaction, and genital image evaluation. They also reported if they ever had partnered sex, condomless sex, and been screened for human immunodeficiency virus (HIV), as well as their lifetime number of penetrative sex partners. Hierarchical logistic and ordinal regression analyses indicated that more positive genital image evaluation, but not the other body image indices, was significantly associated with having had partnered sex and fewer lifetime penetrative sex partners. None of the body image indices were significantly associated with condomless sex. All associations were consistent across men and women. For HIV testing, a significant interaction between genital image evaluation and gender emerged. However, this was reduced to non-significance after controlling for the number of penetrative sex partners. Overall, our findings underline the importance of promoting improved genital image in interventions aimed at increasing positive sexual health behaviors.