Abundant psychological research demonstrates bivariate relationships between individual prosocial propensity, intrinsic connectedness to various social domains, and the enactment of prosocial behavior. More recently, “connectedness” has been positioned as a necessary domain‐specific motivator for enacting prosocial propensity in relevant domains of concern. Our study offers novel contributions to this theory by examining the role of connectedness in driving prosocial behavior within a humanitarian domain in which behavior is enacted in the interest of the global community. Additionally, our research uniquely considers connectedness to multiple social domains concurrently, in order to disentangle any covariance that may be impacting research findings. A parallel mediation model with four mediators (connectedness to community, nation, humanity, and nature) was applied to better understand the effect of prosocial propensity (honesty‐humility) on humanitarian prosocial behavior. The cross‐sectional survey was completed by 715 Australian adults, and support was found for mediation via each of the mediators. Specifically, connectedness to community, to humanity, and to nature each positively affected the relationship between prosocial propensity and prosocial behavior, with the largest effect via connectedness to humanity. Contrastingly, connectedness to nation negatively mediated this relationship, despite being positively correlated with these constructs. These findings highlight the individual difference underpinnings of humanitarian prosocial behaviors and the role of connection to relevant domains in behavior actualization. Fostering connectedness to humanity remains desirable to promote global prosocial outcomes, with future research needed on the interplay between these related levels of connectedness and between connectedness to one's nation and global humanitarian engagement.