Creative idea generation engages complex cognitive functions such as working memory capacity (WMC). The relationship between creativity and WMC has remained inconsistent due to the lack of experimental evidence and the mismatching of WMC tasks and creativity measurements. Therefore, we used both measurements and experiments to explore the effects of WMC on creativity with the matching of task types considered. In Study 1, we conducted multiple measurements to explore the relationship between verbal/visuospatial WMC and verbal/figural creativity and found that participants with higher visuospatial WMC performed better in both types of creativity tasks. Furthermore, we conducted two dual task experiments in Study 2 to explore the causal effects of WMC on creativity. We found only interfering with participants' visuospatial WMC would significantly decrease their creative performances. Moreover, Study 3 ruled out the potential confounding factor of general attention resources in the visuospatial secondary tasks by using a control dual task experiment. These findings indicated that the creative thinking process is likely to rely on visuospatial processing regardless of the form of the presented information.