Despite high levels of muscularity concerns among sexual-minority men, most of the existing literature on the drive for muscularity and muscle dysmorphia focuses on heterosexual men and has mainly been conducted in Western and English-speaking regions. The present study aimed to evaluate the psychometric properties of the Drive for Muscularity Scale (DMS) and the Muscle Dysmorphic Disorder Inventory (MDDI) in Brazilian cisgender gay and bisexual adult men who were 18-50 years old. We evaluated the factor structure of both measures using a two-step, split-sample exploratory (EFA; = 704) and confirmatory (CFA; = 705) factor-analytic approach, which supported the original three-factor structure of the MDDI and resulted in a reduced two-factor solution with 13 items for the DMS. Convergent validity was supported through associations of the DMS and the MDDI with eating disorder symptoms, body-ideal internalization, self-objectification beliefs and behaviors, and body appreciation measures. Additionally, we found good internal consistency, and test-retest reliability of both measures. Results support the validity and reliability of the DMS and the MDDI in Brazilian cisgender gay and bisexual adult men and will support future studies exploring these constructs in Brazilian sexual-minority men.