This study determined the relationship between self-reported and objective measurements of physical activity with adiposity markers in a random sample of community-dwelling older adults. The sample included 439 individuals over 65 years (age 71.1 ± 7.8; 54.2% women). Regular physical activity information was collected using self-reported (questionnaire, 7-day-PAR) and objective measurements (accelerometer ActiGraph GT3X) over 7 days. Anthropometric parameters included body mass index, body fat percentage, and waist circumference. The number of patients considered active was 28% according to the results of 7-day PAR, and 69% according to objective measures of accelerometry. With every daily increase of 10 min of sedentary activity, the BMI, body fat percentage, and waist circumference values increased by 0.04 units, 0.14%, and 0.14 cm, respectively. According to the accelerometry data, being active was a protective factor for presenting obesity criteria (OR = 0.34, CI 95% 0.19–0.59). Objective but non self-reported physical activity was associated with adiposity markers in older adults.