SummaryOverweight and obesity are consistently associated with lower physical activity (PA) levels and greater sedentary behavior (SB) in population studies. To date, no review has evaluated the factors associated with these behaviors in the specific population who have developed obesity/overweight. The aim of this systematic review was to identify the correlates/determinants of SB and PA in adults with overweight and obesity. Five databases were searched for studies, which reported factors or outcomes relating to PA or SB in adults living with overweight/obesity, published from 1980 to 2021. The factors were categorized using a socioecological model, strength, and direction of association. Of 34,058 articles retrieved, 45 studies were included, and 155 factors were identified. Self‐efficacy, intrinsic motivation, exercise enjoyment, self‐perceived good health, and social support were consistently associated with higher levels of PA. Consistent negative correlations were married females, increased BMI, obesity severity, pain, number of comorbidities, lack of time, energy, and willpower, and hilly terrain. Few studies (n = 12) examined SB, and no evidence for consistent associations were found. This review identified several correlates specific to PA in this population. Further studies are required to identify directionality and distal correlates for PA and all correlate levels of SB.