Rationale and Background: : Gender-based violence (GBV), especially domestic violence, is prevalent in Lao PDR. Yet, it is largely a ‘hidden’ and unaddressed problem. Engaging men and boys in GBV prevention first requires an understanding of how men and boys’ perceptions of gender norms and GB. This study is aimed to explore gender and masculinity and men’s level of awareness of GBV, and attitudes towards GBV in Lao PDR and to identify factors associated with men’s awareness of GBV and attitudes towards GBV in Lao PDR. Methodology: : A quantitative research method community-based study was conducted among married men in Vientiane and Champasak provinces, Lao PDR. The sample was married or cohabiting males in a heterosexual union living in the community for at least 1 year. The sample size for the quantitative survey was 680 men and a multi-stage random sampling scheme was applied. Descriptive and Inferential statistics were applied. A bivariate logistic regression model followed by multivariable analysis was performed to identify the associated factors of GBV. Results: : About 44.6% of men in particular suffered more severe forms of physical violence. Overall, 43.2% of male participants had positive attitudes towards gender equality and 67.1% of male participants had positive attitudes towards GBV. Overall, 99.4% of male participants ever reported physical violence during their lifetime Gender Equality Matters while 76% reported having physical violence during the last year. About one-fourth of participants (20.3%) had sexual violence during the last year. The majority of participants (84%) had good knowledge of GBV, but 46.7% had high knowledge of different types of GBV. Persons living with their family (AOR: 2.9; 95% CI: 01.1-7.2); attitudes towards GBV (AOR: 5.4; 95% CI: 3.7-9.6); men’s awareness of the effectiveness of strategies to engage men in GBV prevention (AOR: 12.2; 95% CI: 4.7-31.7) were significantly correlated with knowledge of GBV. While factors statistically significant associated with positive attitudes towards GBV were non-Lao-Tai ethnic (AOR: 0.2; 95% CI: 0.1-0.4); knowledge of GBV (AOR: 4.9; 95% CI: 3.1-7.9); and men’s awareness on the effectiveness of strategies to engage men in GBV prevention (AOR: 0.2; 95% CI: 0.1-0.3). Conclusion: This study highlights the good knowledge of GBV among male participants and the low knowledge of different types of GBV. It also revealed the positive attitudes towards GBV and high Gender Equality Matters (GEM). Factors statistically significant associated with knowledge of and attitudes towards GBV among male participants were socio-demographic characteristics, attitudes towards GBV, and men’s awareness of the effectiveness of strategies to engage men in GBV prevention. Men-oriented programs, such as those involving men, also address gender norms, with promising results including increased equitable attitudes and reduced self-reported gender-based violence perpetration.