Based on the original 22-item single-factor questionnaire, the 10-item second-order Acceptance and Action Questionnaire for Weight-Related Difficulties–Revised (AAQW-R) was developed for measuring weight-related experiential avoidance. This instrument showed good psychometric properties, and it has been validated to different contexts. However, no Spanish validation has been conducted, to date. Therefore, the aim of this study was to analyze the psychometric properties of the Spanish version of the instrument in a sample of adults from the Spanish context across the whole body mass index spectrum (N = 393). Confirmatory factor analysis was performed to examine the fit of the first- and second-order AAQW-R structures. Internal reliability, construct validity, external reliability, and sensitivity to change were also analyzed. The Spanish AAQW-R presented a good fit to the data, the overall scale and subscale scores showed acceptable-to-good internal consistencies, and adequate construct validity. Likewise, test–retest reliability parameters were high, and the instrument showed sensitivity to change. The findings demonstrate that the Spanish AAQW-R is an instrument with good psychometric properties, supporting its use for measuring adults’ weight-related experiential avoidance in both research and clinical settings within the Spanish context.