Even though many studies have examined the link between individuals' perceived general similarity to their romantic partners and their own relationship satisfaction, there are not many studies focusing on the impact of perceived general similarity reported by the partner. The present work uncovers the potential mediating roles of one's and the partner's attributional confidence in the effects of one's and the partner's perceived general similarity on relationship satisfaction. To investigate the mechanisms, two studies were conducted at individual and dyadic levels. A total of 395 individuals (51.4% female) aged 17–67 (M = 22.06, SD = 4.68) in unmarried opposite‐gender relationships were recruited in Study 1 and 227 unmarried opposite‐gender couples were employed in Study 2. Across two studies, the indirect effect of perceived general similarity on relationship satisfaction via attributional confidence was significant. In particular, the actor effects of perceived general similarity on relationship satisfaction were mediated by the actor effects of attributional confidence. Moreover, the partner effects of perceived general similarity on relationship satisfaction were mediated by partner attributional confidence (i.e., one's partner's perceived general similarity on one's relationship satisfaction via one's partner's attributional confidence). The present findings shed light on the mechanisms through which perceived general similarity fosters relationship satisfaction among opposite‐gender relationships.