<p>Social media has become a strategic tool for firms worldwide to drive customer engagement (CE) and enhance business performance, yet limited research has systematically examined how social media content strategies (SMCSs) perform across cultural contexts. To address this gap, we conceptualize SMCS along three key dimensions—content characteristics, content source, and content valence—and develop a meta-analytic model grounded in signaling theory. Drawing on 148 empirical studies comprising 869 effect sizes, we examine the mediating role of CE, through which these content dimensions indirectly impact brand, product-market, and financial market performance. We also assess how national cultural values (i.e., individualism, uncertainty avoidance, power distance, masculinity, long-term orientation, and indulgence) moderate the content–engagement link. The findings reveal that CE serves as a key mechanism linking SMCSs to firm performance. Moreover, the strength and direction of these effects vary systematically across cultural values, highlighting important boundary conditions caused by national culture for social media content effectiveness. This study advances research at the intersection of social media and international business by providing a systematic cross-cultural account of how digital content strategies translate into engagement and performance outcomes.</p>