A primary task of adolescence and young adulthood is to form and develop healthy romantic relationships. While the importance of sibling and romantic relationships have been examined separately, only recently have researchers begun to explore links between the two. The purpose of the present study was to investigate the connection between romantic competence and sibling relationships, especially sibling warmth and sibling conflict, as well as the role of sibling gender constellation in college-aged young adults. This study aimed to examine (a) whether there is an association between sibling relationship quality, such as sibling warmth and sibling conflict, and perceived romantic competence, and (b) the role of sibling gender constellation on the relationship between sibling relationship quality (sibling warmth and sibling conflict) and perceived romantic competence among undergraduate students. Correlation analyses indicated there was no statistically significant correlation between sibling warmth and perceived romantic competence (p > .05), whereas sibling conflict was statistically negative correlated with perceived romantic competence (p < .01). While sibling gender constellation did not have an interaction effect with sibling conflict on perceived romantic competence, which means sibling gender constellation did not have a moderating effect on the relationship between sibling conflict and perceived romantic competence. Limitations and applications of the present study were also discussed.