The “brain drain” hypothesis posits that the mere presence of a smartphone may occupy limited-capacity cognitive resources and, as a result, negatively impact cognitive performance. In this research, to assess the strength of evidence for this effect, we conducted a systematic review and meta-analysis (k = 56, n = 7093). While results are nuanced across cognitive functions, the meta-analysis provides little evidence to support the existence of a brain drain effect associated with the mere presence of a smartphone. The pooled effect for four of the five cognitive domains does not support the hypothesis and, while the effect is consistent with the claim for working memory, its magnitude is far smaller than early seminal work. The overall combined effect is not statistically different from zero and, given conservative equivalence bounds, it is likely equivalent to zero. The analysis also finds that there is substantial methodological heterogeneity and poor statistical power in the domain. Overall, the findings suggest that there is little empirical support for the brain drain effect due to the mere presence of a smartphone and, given methodological concerns, the extent to which the current body of literature can support or refute the hypothesis is limited.