--- - |2+ Abstract Objective Identity formation is a key developmental milestone for adolescents and young adults (AYAs). Autobiographical memory and future‐thinking are crucial cognitive processes underpinning this, which may be impacted by cancer experiences. We know little about how these processes might be related to AYAs' adjustment to cancer, quality of life (QoL), and mental health outcomes. Methods We examined autobiographical memory and future‐thinking processes, and their relationship with mental health outcomes, among 77 AYA cancer survivors (Mage = 22.3 years, 59.7% female), compared with 62 community‐based controls (Mage = 23.3 years, 50% female). Participants completed the Life Narratives Interview, Future Imaginings Task, measures assessing depression, anxiety, QoL, and cancer‐related identity. We coded two facets of autobiographical thinking: thematic content and specificity. Results Relative to controls, survivors recounted more negative life narratives (P = .000). Survivors' memories and future lives were more health/illness‐focused (P = .000) and they remembered past events with greater specificity (P = .007) than controls. In contrast, survivors imagined their future lives with less specificity than controls (P = .000). Regression analyses highlighted that being female, greater identification as a “cancer survivor,” worse depression, and recent cancer treatment‐completion significantly predicted maladaptive autobiographical thinking processes. Conclusions These findings point to key modifiable cognitive processes relevant to AYAs' cancer‐related adjustment and future mental health. To bolster resilience into longer‐term survivorship, clinicians could adapt existing evidence‐based, cognitive‐behavioural interventions to assist AYAs to imagine future events in greater detail. - Psycho-Oncology, EarlyView.