AbstractBackgroundMany individuals living with and beyond cancer (LWBC) have ongoing quality of life (QoL) issues, including fatigue. The World Cancer Research Fund (WCRF) provides health behaviour recommendations for people LWBC, and there is some evidence linking adherence to these with improved QoL.MethodsAdults LWBC (specifically breast, colorectal or prostate cancer) completed a survey covering health behaviours (diet, physical activity, alcohol consumption and smoking), fatigue (FACIT‐Fatigue Scale, version 4) and a broad measure of QoL (EQ‐5D‐5L descriptive scale). Participants were categorised as meeting/not meeting WCRF recommendations, using the following cut‐offs classified as meeting the guidelines: ≥150 min physical activity/week, fruit and vegetables (≥5 portions/day), fibre (≥30 g fibre per day), free sugar (<5% of total calories from free sugar), fat (<33% total energy), red meat (<500 g/week), processed meat (none), alcohol consumption (<14 units/week) and not a current smoker. Logistic regression analyses explored associations between WCRF adherence and fatigue and QoL issues, controlling for demographic and clinical variables.ResultsAmong 5835 individuals LWBC (mean age: 67 years, 56% female, 90% white, breast 48%, prostate 32% and colorectal 21%), 22% had severe fatigue and 72% had 1+ issue/s on the EQ‐5D‐5L. Adhering to physical activity recommendations (odds ratio [OR] = 0.88, confidence interval [CI] = 0.77–0.99), meeting various dietary recommendations (fruit and vegetables OR = 0.79; CI = 0.68–0.91, free sugar OR = 0.85; CI = 0.76–0.96, fat OR = 0.71; CI = 0.62–0.82, red meat OR = 0.65; CI = 0.50–0.85) and not smoking (OR = 0.53, CI = 0.41–0.67) were associated with decreased odds of experiencing severe fatigue. Adhering to physical activity guidelines (OR = 0.71, CI = 0.62–0.82) was also associated with decreased odds of having 1+ QoL issue/s.ConclusionsAdherence to various WCRF recommendations, particularly the recommendation for physical activity, was associated with less fatigue and better QoL in a large UK cohort of people living with and beyond breast, colorectal or prostate cancer. Multi‐component interventions designed to support people LWBC to improve health behaviours, in line with the levels recommended by the WCRF, may also improve QoL.