ObjectivesTraditionally, the literature investigating patient‐reported outcomes in relation to cancer survival focused on negative factors such as distress. Meta‐analyses in this field have provided a clear identification of negative affect that reduce cancer survival (e.g., depression). Nevertheless, positive psychological factors and especially positive affect might be equally crucial for cancer survival but have been neglected so far. While studies in this domain have been conducted, they remain less numerous and have produced mixed results.MethodsA pre‐registered systematic review and meta‐analysis (https://osf.io/jtw7x) aimed at identifying the positive affect linked to mortality in cancers were conducted. Four databases (Pubmed, PsycINFO, Embase, and Cochrane Library) were searched to find longitudinal studies linking positive affect to survival in cancers. Two reviewers completed each stage of the study selection process, the data extraction, and the Quality in Prognosis Studies risk of bias assessments.ResultsTwenty‐four studies involving 822,789 patients were included based on the 2462 references identified. The meta‐analysis reveals that positive affect is associated with longer survival (Hazard Ratio [HR] = 0.91; 95% CI [0.86, 0.96], z = −3.58, p < 0.001) and lower mortality (Odd Ratio [OR] = 0.59; 95% CI [0.45, 0.78], z = −3.70, p < 0.001). Sub‐group analyses indicated that the main predictors of survival are emotional and physical well‐being, optimism, and vitality.ConclusionThis work emphasizes the need to consider the role of affective mechanisms in patients with cancer, including their levels of well‐being or optimism to provide the most favorable conditions for survival. Therefore, stronger and continuous effort to improve patients' positive affect could be particularly beneficial for their life expectancy.