Although recent correlational studies have found a relationship between fantasy orientation (FO; i.e., a child’s propensity to play in a fantastical realm) and higher order cognitive skills called executive functions (EFs), no work has addressed the causality and directionality of this relationship. The current study experimentally examined the directionality of the observed relationship between FO and EF development in preschool-aged children through an innovative play intervention employing a randomized controlled design. A sample of 110 children between the ages of 3 and 5years were randomly assigned to one of three conditions: fantastical pretend-play intervention, non-imaginative play intervention, or business-as-usual control. Results revealed that children who participated in a 5-week fantastical pretend-play intervention showed improvements in EFs, whereas children in the other two conditions did not. Within the fantastical pretend-play condition, children who were highly engaged in the play and those who were highly fantastical demonstrated the greatest gains in EFs. These data provide evidence for the equifinal relationship between fantasy-oriented play and EF development, such that engaging in fantasy-oriented play may be one of many ways to directly enhance EF development.