There are long-held concerns regarding the impact of screen media on children's cognitive development. In particular, fast pace and fantastical events have been theorized to deplete children's cognitive resources, leading to reductions in their attention and executive functions (EF). To date, however, empirical tests of short-term effects of media pace and fantasy on children's cognition have yielded mixed findings. In the present study, we conducted meta-analytic syntheses of previous findings on the impact of pace (19 studies involving 141 effect sizes based on 1431 1.5- to 10-year-olds) and fantasy (16 studies involving 121 effect sizes based on 1297 1.5- to 6-year-olds) on children's attention and EF immediately after media exposure. Overall, our findings revealed that media pace does not affect children's cognition (d = -0.123, 95% CI [-0.331, 0.086], p = 0.23). In contrast, media fantasy was found to have a negative effect, wherein children who watched fantastical media compared to realistic media performed worse on attention and EF tasks immediately post-viewing (d = -0.244, 95% CI [-0.442, -0.046], p = 0.02). The large heterogeneity in effects for both pace (95% PI [-1.100, 0.854]) and fantasy (95% PI [-1.120, 0.632]), however, points to the complexity in conditions under which media exposure differentially impacts children's cognition--in some cases, negatively, in others positively, or not at all. Of the moderators tested, our findings point to the influence of facet of cognition examined (attention, cognitive flexibility, higher order EF, inhibitory control, working memory) on the strength of short-term media exposure effect.