Abstract Background The elderly are faced with health problems such as cardiovascular diseases, type II diabetes mellitus, kidney disease, arthritis and other musculoskeletal problems, which can be linked to obesity and overweight. The aim of this study was to determine the prevalence of obesity and overweight and its associated factors amongst registered pensioners in Ghana. Methods A cross-sectional study was conducted among members of the national pensioners association of Ghana. 4813 pensioners took part in the study. Thirteen study centers were used in the study with at least one center per regional capital. Questionnaires, physical examinations, blood and urine sample examinations were carried out. Results Overall, 16.3% of the pensioners were obese while 30.0% were overweight. Prevalence of obesity among males and females were 8.0% and 34.5% respectively. Pensioners who were hypertensive had 1.8 times the odds (95% CI = 1.5–2.0) of being obese/overweight. Serum triglycerides levels of 2.26 mmol/L (200 mg/dL) or more, were associated with 80% chance of obesity and overweight (OR = 1.8, 95% CI = 1.3 - 2.5). There was 30% increase in arthritis among obese/overweight pensioners compared to normal/underweight pensioners. Obesity and overweight pensioners were more likely to be using eyeglass (OR = 1.7, 95% CI = 1.3–2.2) and less likely to report hearing loss (OR = 0.7, 95% CI =0.5–1.0). Conclusion The prevalence of obesity among the elderly in Ghana is high. Age had an inverse linear relationship with BMI among pensioners. Hypertension, arthritis and dyslipidemia were associated with obesity among registered pensioners.