Physical activity and sedentary behavior are modifiable risk factors for non-communicable disease and healthy ageing, however the majority of older adults remain insufficiently active. Digital behavior change interventions (DBCI) have the potential to reach many older adults to promote physical activity and reduce sedentary time. This study aims to assess the efficacy of DBCI interventions in older adults (≥50 years) on physical activity and sedentary behavior. A systematic review of major databases from inception to 03/2018 was undertaken. Randomized controlled trials (RCT) or pre-post interventions assessing effects of DBCI on physical activity and/or sedentary behavior in older adults (≥50 years) were included. Random effects meta-analyses were carried out. Twenty-two studies were included, including 1757 older adults (mean age = 67 years, %male = 41), 68% showed moderate-high risk of bias. Meta-analyses suggested that DBCI increased total physical activity among RCT studies (n = 8) (SMD = 0.28; 95%CI 0.01, 0.56; p = 0.04) and pre-post studies (n = 6) (SMD = 0.25; 95%CI 0.09, 0.41; p = 0.002), increased moderate-to-vigorous physical activity (SMD = 0.47; 95%CI 0.32, 0.62, p < 0.001; MD = 52 min/week) and reduced sedentary time (SMD = −0.45; 95%CI −0.69, −0.19; p < 0.001; MD = 58 min/day). Reductions in systolic blood pressure (−11 bpm; p = 0.04) and improvements in physical functioning (p = 0.03) were also observed. DBCI may increase physical activity and physical functioning, and reduce sedentary time and systolic blood pressure in older adults, however more high-quality studies are required. •Digital behavior change interventions have potential to increase physical activity and reduce sedentary time in older adults•Digital behavior change interventions may improve physical functioning and reduce systolic blood pressure•The most common behavior change techniques found in the interventions were social support, goal setting and feedback•A minimum of 3 behavior change technique clusters were required for significant effects on physical activity