Previous research suggests that women without children are perceived negatively by others and experience adverse outcomes in various settings. This study investigated psychosocial justifications of prejudice toward childfree women. Participants (N = 891) completed measures of right-wing authoritarianism (RWA), the internal (IMS-S) and external (EMS-S) motivations to respond without sexism, and prejudice toward childfree women (i.e., perceived disadvantages of being childfree, evaluations of childfree women, and perceptions of childfree women’s warmth). Most participants also completed one or more justification measures of hostile sexism (HS), benevolent sexism (BS), gender-specific system justification (GSSJ), and femininity ideology. Results indicated that greater RWA was directly associated with greater perceived childfree disadvantages and coldness in childfree women. Additionally, greater IMS-S was directly associated with fewer perceived disadvantages, favorable evaluations, and greater perceived warmth; and greater EMS-S was directly associated with more negative evaluations and perceived coldness. Greater BS and GSSJ were also associated with greater disadvantages. Furthermore, femininity ideology was directly associated with greater disadvantages, unfavorable evaluations, and perceived coldness. In mediational analyses, IMS-S and EMS-S were associated with greater disadvantages, unfavorable evaluations, and perceived coldness indirectly through femininity ideology. EMS-S was also associated with greater disadvantages and unfavorable evaluations indirectly through BS. This study makes a unique contribution to the literature on attitudes toward childfree women by not only replicating that childfree prejudice persists, but also documenting why it potentially exists. Additionally, by identifying several psychosocial constructs that may justify childfree prejudice, this study suggests future research and possible interventions to reduce childfree prejudice.