<p>While generally reliable, human memory is susceptible to distortions such as false memories. This study investigates the relationships among the emotional valence of events, mood states, and the formation of false autobiographical memories, applying the blind implantation method. We examine the impact of positive and negative moods, combined with the emotional valence of events (negative vs. positive), on false belief and recollection ratings. We conducted two preliminary studies to develop an online mood induction and select critical and noncritical autobiographical events. In the main experiment, 715 adults completed a list of 20 autobiographical events. The participants who had not experienced certain critical events were invited to a second phase, resulting in a final sample of 242 participants (130 female, 108 male, and four others), aged 19–81 years (<i>M</i> = 40.35, <i>SD</i> = 12.64). After experiencing the mood induction, they were presented with a survey suggesting that they had previously reported experiencing a critical event. False beliefs and memories were implanted in 6% (<i>n</i> = 15) to 34% (<i>n</i> = 83) of the cases. While mood did not affect false belief and recollection ratings, negative events led to greater false belief and recollection than positive events did, aligning with the associative activation model and fuzzy-trace theory. These findings highlight the need for caution in settings (e.g., therapy), where possible suggestive techniques could inadvertently implant false traumatic memories.</p>