ABSTRACT The IKEA effect refers to people's tendency to overestimate the value of items they personally assembled or assisted in creating. The current meta‐analysis ( k = 55, N = 5,454), synthesizes data from empirical studies assessing the relationship between self‐assembly and product valuation to estimate the average effect size of the phenomenon, test its main and secondary outcomes, and assess potential boundary conditions. The results point to a significant moderate impact of self‐assembly labor on valuation ( d = 0.57, p < 0.005), as well as a host of secondary outcomes, including liking, self‐concept, and sense of ownership. Moreover, the observed effects remained quite robust in the face of various moderators such as product customization and tangibility. By integrating over a decade of research, this meta‐analysis offers a comprehensive quantitative assessment of the IKEA effect, clarifies its psychological underpinnings, and highlights key directions for future research.