Objective: There may be age-related differences in the impact of weight change on health. This study systematically reviewed the evidence on the relationship between weight change and all-cause mortality in adults aged 65 years and older. Method: MEDLINE, EMBASE and CINAHL were searched from inception to 11th June 2020, PROSPERO CRD 42019142268. We included observational studies reporting on the association between weight change and all-cause mortality in older community-dwelling adults. A random-effects meta-analysis was performed to calculate pooled hazard ratios, and scored based on the Agency for Healthcare Research and Quality (AHRQ) guidelines. Results: A total of 30 studies, including 1,219,279 participants with 69,255 deaths, demonstrated that weight loss was associated with a 59% increase in mortality risk (HR: 1.59; 95%CI, 1.45–1.74, p < 0.001). The 27 studies which reported outcomes for weight gain (1,210,116 participants with 65,481 deaths) indicated that weight gain was associated with a 10% increase in all-cause mortality (HR:1.10; 95%CI:1.02, 1.17, p = 0.01). Four studies investigated weight fluctuation (2,283 events among 6,901 participants), which was associated with a 63% increased mortality risk (HR: 1.63; 95%CI: 1.37, 1.94, p < 0.001). No evidence of publication bias was observed (all p > 0.05). Conclusion: For community-dwelling older adults, weight changes (weight loss, gain or weight fluctuation) are associated with an increased risk of all-cause mortality risk relative to stable weight. Further research is needed to determine whether these associations vary depending upon initial weight, and whether or not the weight loss/gain was intentional.