Ecological momentary assessment is an excellent tool for the measurement of different day-to-day domains in patients and capturing real-world and real-time data. The purpose of this review is to evaluate feasibility in current ecological momentary assessment studies on emotional and behavioral functioning, functional impairments, and quality of life patients with an attention-deficit/hyperactivity disorder diagnosis. This systematic review follows the recommendation of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines selecting articles published from January 1, 1990, up to the latest access on May 2018, identifying a pool of 23 eligible studies. Twenty-three studies demonstrate the validity of ecological momentary assessment methodology in evaluating different aspects of patients with attention-deficit/hyperactivity disorder. Fifteen studies focus on the child’s or adolescent’s daily behavior, while eight studies only focus on adults. The studies presented in this review monitored patients and their families over a maximum period of 28 days. We can conclude that ecological momentary assessment can be successfully implemented with attention-deficit/hyperactivity disorder patients to evaluate diverse backgrounds. However, more studies are needed with a longer monitoring period, especially in adolescents, to determine the effectiveness of ecological momentary assessment on patients with attention-deficit/hyperactivity disorder.