Prior research has indicated that beliefs in rape myths can influence juror decision-making in cases involving sexual assault, however, the phenomenon has been typically examined in relation to victim and defendant believability, as well as final verdicts. The current study observed mock jurors’ evaluations of third-party witness evidence in alleged rape cases to determine whether these judgements were influenced by inherent rape myths. Participants (N = 196) took part in a mock juror experiment that included evidence from an eyewitness that was either in support of the defence, prosecution, or neutral. We found that males and individuals holding strong beliefs in rape myths were more likely to find defendants not-guilty. Additionally, participants endorsing rape myths were also more likely to view eyewitness evidence favourably, but only when it was in support of the defence. Our findings suggest that personal biases can influence the level of credence jurors place on case evidence, potentially through a confirmation bias.