Background: Public health guidelines suggest that physical activity can be accumulated in multiple short bouts dispersed through the day. A synthesis of the evidence for this approach is lacking. Objective: Our objective was to undertake a systematic review and meta-analysis to examine if exercise interventions consisting of a single bout of exercise compared with interventions comprising the same total duration, mode, and intensity of exercise accumulated over the course of the day have different effects on health outcomes in adults. Methods: Six electronic databases were searched (Jan 1970–29 August 2018). Two authors identified studies that evaluated the effects of a single bout of exercise compared with the same intensity, total duration, and mode of exercise accumulated in multiple bouts over the course of a day, in community-dwelling adults. Risk of bias was assessed using the Cochrane Collaboration tool. Pooled effects were reported as standardised mean differences (MDs) and 95% confidence intervals (CIs) using a random effects model. Results: A total of 19 studies involving 1080 participants met the inclusion criteria. There were no differences between accumulated and continuous groups for any cardiorespiratory fitness or blood pressure outcomes. A difference was found in body mass changes from baseline to post-intervention in favour of accumulated exercise compared with continuous (MD − 0.92 kg, 95% CI − 1.59 to − 0.25, I 2 = 0%; five studies, 211 participants). In subgroup analyses, accumulating > 150 min of weekly exercise in multiple bouts per day resulted in small effects on body fat percentage (combined post-intervention and change from baseline values: MD − 0.87%, 95% CI − 1.71 to − 0.04, I 2 = 0%; three studies, 166 participants) compared with 150 min of exercise amassed via single continuous bouts per day. There was a decrease in low-density lipoprotein (LDL) cholesterol with accumulated versus continuous exercise (MD − 0.39 mmol/l, 95% CI − 0.73 to − 0.06, I 2 = 23%; two studies, 41 participants). No differences were observed for any other blood biomarker (total cholesterol, high-density lipoprotein cholesterol, triglycerides, fasting blood glucose, and fasting insulin). Conclusions: There is no difference between continuous and accumulated patterns of exercise in terms of effects on fitness, blood pressure, lipids, insulin and glucose. There is some evidence from a small number of studies that changes in body mass and LDL cholesterol are more favourable following the accumulated condition. Collectively our findings suggest that adults are likely to accrue similar health benefits from exercising in a single bout or accumulating activity from shorter bouts throughout the day. This review will inform public health guidelines for physical activity at the global and national levels (PROSPERO 2016 CRD42016044122).