Inconsistencies in the Female Sexual Function Index (FSFI) factor structure and current research and clinical guidelines highlight the need for continued exploration of its psychometric evidence. Furthermore, only one study has assessed its measurement invariance (MI), while the only FSFI validation conducted in Chile lacks quality and representativity. Therefore, this study aimed to evaluated the FSFI in a Chilean sample (n = 2595), examining MI across relationship status, age groups, regions of the country, BDSM practices, and paraphilic interests. Confirmatory factor analysis supported a six-factor structure. Criterion-related validity indicated modest-to-moderate effects in satisfaction differences based on relationship status, regions, and BDSM practices. MI was achieved across socio-demographic variables at the factor covariance level. While acknowledging the absence of a clinical group for female sexual dysfunction (FSD) diagnosis, potential pandemic-related impact on scores, online methodology biases, and limited diversity in gender and sexual orientation, our findings supports the FSFI as a valuable research tool for female sexual function and wellbeing. This study significantly expands the applicability of the FSFI and underscores its measurement invariance across sociodemographic factors, as well as its applicability in the Chilean context.