Customer engagement (CE) is a marketing concept of great importance and the rise of social media has further amplified the importance of this concept. Yet, our understanding of the progress of CE research remains limited due to the absence of a one-stop state-of-the-art overview of the concept that considers its manifestation on social media. To address this gap, we review CE research on social media since the beginning of the present millennium using the PRISMA protocol for systematic reviews. The outcome of our review reveals the antecedents, decisions, and outcomes; the theories, contexts, and methods; and the ways forward for advancing knowledge, improving representation, and enhancing rigor with respect to future research on CE and social media.