Acceptance and commitment therapy (ACT) is an emerging evidenced-based practice based on a psychological flexibility model encompassing six processes, including acceptance, cognitive defusion, self-as-context, being present, values, and committed action. ACT aims to improve overall psychological flexibility and the six processes. This systematic review and meta-analysis examined the effects of ACT on measures of purported processes among family caregivers. Four electronic databases were searched from the date of inception of each database to March 30, 2020.