Abstract Background Physical function is an independent predictor of numerous chronic diseases, but its association with all-cause mortality in older adults diagnosed with cancer has received little attention. The aim of this study was to conduct a systematic review and meta-analysis on the prospective association between physical function and all-cause mortality in older adults diagnosed with cancer. Methods Two authors systematically searched MEDLINE, EMBASE, and SPORTDiscus databases. Prospective studies reporting associations of baseline physical function with all-cause mortality in patients aged 60 years or older diagnosed with any type of cancer were included. Hazard ratios (HR) with associated 95% confidence intervals (CI) were extracted from studies for all-cause mortality, and pooled HRs were then calculated using the random-effects inverse-variance model with the Hartung–Knapp–Sidik–Jonkman adjustment. Results Data from 25 studies with 8109 adults diagnosed with cancer aged 60 and older were included in the study. Higher levels of physical function (short physical performance battery, HR = 0.44, 95% CI 0.29–0.67; I2 = 16.0%; timed up and go, HR = 0.40, 95% CI 0.31–0.53; I2 = 61.9%; gait speed, HR = 0.41, 95% CI 0.17–0.96; I2 = 73.3%; handgrip strength: HR = 0.61 95% CI 0.43–0.85, I2 = 85.6%; and overall, HR = 0.45 95% CI 0.35–0.57; I2 = 88.6%) were associated with a lower risk of all-cause mortality compared to lower levels of functionality. Neither age at baseline nor length of follow-up had a significant effect on the HR estimates for lower all-cause mortality risk. Conclusion Physical function may exert an independent protective effect on all-cause mortality in older adults diagnosed with cancer.