Objective: To explore changes in mindfulness and cognitive flexibility before and within 24 h after ayahuasca use. Methods: Forty-eight participants (54% female) were assessed on measures of mindfulness (Five Facets Mindfulness Questionnaire (FFMQ)), decentering (Experiences Questionnaire (EQ)), and cognitive flexibility (Cognitive Flexibility Scale (CFS)), and completed the Stroop and Wisconsin Picture Card Sorting Task (WPCST) before drinking ayahuasca, and again within 24 h. Results: Mindfulness (FFMQ total scores and four of the five mindfulness facets: observe, describe, act with awareness, and non-reactivity) and decentering (EQ) significantly increased in the 24 h after ayahuasca use. Cognitive flexibility (CFS and WPCST) significantly improved in the 24 h after ayahuasca use. Changes in both mindfulness and cognitive flexibility were not influenced by prior ayahuasca use. Conclusions: The present study supports ayahuasca’s ability to enhance mindfulness and further reports changes in cognitive flexibility in the ‘afterglow’ period occur, suggesting both could be possible psychological mechanisms concerning the psychotherapeutic effects of ayahuasca. Given psychological gains occurred regardless of prior ayahuasca use suggests potentially therapeutic effects for both naïve and experienced ayahuasca drinkers.