Abstract Background older people with cancer are at risk of complex and fluctuating health problems, but little is known about the extent to which their well-being changes in the last years of life. Objective to examine changes in physical, psychological and social well-being in the last 5 years of life of older people with cancer. Design prospective cohort study. Setting Belgium, the Netherlands. Participants people with a new primary diagnosis of breast, prostate, lung or gastrointestinal cancer, aged ≥70 years, life expectancy >6 months, were recruited from nine hospitals. We analysed data of deceased patients. Methods data were collected from participants around diagnosis, and after 6 months, 1, 3 and 5 years through structured questionnaires administered through interviews or as self-report. Outcomes were physical, emotional, social, role functioning (EORTC QLQ-C30), depressive symptoms (GDS-15), emotional and social loneliness (Loneliness Scale). We conducted linear mixed model analyses. Results analysing 225 assessments from 107 deceased participants (assessments took place between 1,813 and 5 days before death), mean age at baseline 77 years (standard deviation: 5.2), we found statistically significant deterioration in physical functioning (b = 0,016 [95%confidence interval 0.009–0.023]), depressive symptoms (b = −0,001 [−0.002 to 0.000]) and role functioning (b = 0.014 [0.004–0.024]). Changes over time in emotional and social functioning and in social and emotional loneliness were smaller and statistically non-significant. Conclusions care towards the end of life for older people with cancer needs to put their social and psychological well-being at the centre, alongside physical needs. Future research should focus on understanding inter-individual variation in trajectories.