The present review was to evaluate the available evidences for the health impact of physical activity (PA) and sedentary behaviors (SB) in obese adults at pre-and post-bariatric surgery (BS). Articles were identified through electronic search using PubMed and Google Scholar databases. The search terms included “bariatric surgery,” “weight loss surgery,” “obesity surgery,” “weight reduction surgery,” “physical activity, “exercise,” “resistance training,” “weight training,” “strength training,” and “sedentary”. Inclusion terms were human, adults 18+ years, have clear description of PA, and published in a peer-reviewed English journal within the past 10 years. Potential articles were initially screened by titles and abstracts. Then, relevant articles were assessed, and data were extracted from the eligible articles. The initial search identified 833 records. However, after reading the titles and abstracts and removing duplicates, 62 articles remained. The findings showed that almost all studies on PA interventions before BS improved physical function and capacity, and quality of life. BS by itself increases PA among patients post-surgery. The increased PA during the first year of post-surgery were mostly maintained through several years later. However, in one study, PA at year seven post-surgery was still below PA recommendations. Another study observed little time spent in light intensity PA or in moderate to vigorous PA (MVPA) after BS. Despite that, there appears a dose-response association between more steps/more MVPA and greater weight loss. The average steps/day was between 6375 and 9108. A substantial increase in activity energy expenditure was reported from 345.4 ± 172.8 MET-min/week preoperatively to 672.8 ± 227.8 MET-min/week at 6 months postoperatively. The correlation between self-reported and sensor-based MVPA was weak. Components of the interventions in the present review were varied; some studies involved supervised exercise programs with fair details, whilst others were counselling based trials with little monitoring of PA intensity. In some of the studies investigating weight loss caused by exercise following BS, the training program is poorly reported, and the sample size, selection criteria, and follow-up time vary greatly across studies. Most self-reported changes in PA predicted postoperative weight loss. However, their validity has been questioned. Moreover, daily time spent in SB among obese patients appears excessive. In general, research supports the importance of increased PA and reduced SB in the context of BS as each is being associated with more favorable weight loss and improved health outcomes.