Low levels of physical activity (PA) are associated with poorer health outcomes. The perioperative encounter (extending from initial contact in primary care to beyond discharge from hospital) is potentially a good time to intervene, but data regarding the effectiveness of interventions are scarce. To address this, we systematically reviewed existing literature to evaluate the effectiveness of interventions applied perioperatively to facilitate PA in the medium to long-term (at least six months after the intervention). In this systematic review and meta-analysis, we searched Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, CINAHL, Embase, PsycInfo, and SPORTDiscus from database inception to October 22nd 2020, with an updated search done on August 4th 2022. We searched clinical trials registers, and conducted forward- and backward-citation searches. We included randomised controlled trials and quasi-randomised trials comparing PA interventions with usual care, or another PA intervention, in adults who were scheduled for, or had recently undergone, surgery. We included trials which reported our primary outcomes: amount of PA or whether participants were engaged in PA at least six months after the intervention. A random effects meta-analysis was used to pool data across studies as risk ratios (RR), or standardised mean differences (SMDs), which we interpreted using Cohen. We used the Cochrane risk of bias tool and used GRADE to assess the certainty of the evidence. This study is registered with PROSPERO, CRD42019139008. We found 57 trials including 8548 adults and compared 71 interventions facilitating PA. Most interventions were started postoperatively and included multiple components. Compared with usual care, interventions may slightly increase the number of minutes of PA per day or week (SMD 0.17, 95% CI 0.09-0.26; 14 studies, 2172 participants; I2=0%), and people's engagement in PA at the study's end (RR 1.19, 95% CI 0.96-1.47; 9 studies, 882 participants; I2=25%); this was moderate-certainty evidence. Some studies compared two different types of interventions but it was often not feasible to combine data in analysis. The effect estimates generally indicated little difference between intervention designs and we judged all the evidence for these comparisons to be very low certainty. Thirty-six studies (63%) had low risk of selection bias for sequence generation, 27 studies (47%) had low risk of bias for allocation concealment, and 56 studies (98%) had a high risk of performance bias. For detection bias for PA outcomes, we judged 30 studies (53%) that used subjective measurement tools to have a high risk of detection bias. Interventions delivered in the perioperative setting, aimed at enhancing PA in the medium to long-term, may have overall benefit. However, because of imprecision in some of the findings, we could not rule out the possibility of no change in PA. National Institute for Health Research Health Services and Delivery Research programme (NIHR127879).