We provide a systematic review of interventions utilizing mobile technology to alter physical activity, sedentary behavior, and sleep among adults aged 50 years and older. A systematic search identified 52 relevant articles (randomized control trial [RCT], quasi-experimental, pre/post single-group design). Of 50 trials assessing physical activity, 17 out of 29 RCTs and 13 out of 21 trials assessed for pre/post changes only supported the effectiveness of mobile interventions to improve physical activity, and 9 studies (five out of 10 RCTs and all four pre/post studies) out of 14 reduced sedentary behavior. Only two of five interventions improved sleep (one out of two RCTs and one out of three pre/post studies). Text messaging was the most frequently used intervention (60% of all studies) but was usually used in combination with other components (79% of hybrid interventions included SMS, plus either web or app components). Although more high-quality RCTs are needed, there is evidence supporting the effectiveness of mHealth approaches in those aged 50 years and older.