Care plans can reduce care fragmentation for children with medical complexity (CMC); however, implementation is challenging. Mobile health innovations could improve implementation. This mixed methods study's objectives were to (1) evaluate feasibility of mobile complex care plans (MCCPs) for CMC enrolled in a complex care program and (2) study MCCPs' impact on parent engagement, parent experience, and care coordination. MCCPs were individualized, updated quarterly, integrated within the electronic health record, and visible on parents' mobile devices via an online portal. In 1 year (September 1, 2016, to August 31, 2017), 94% of eligible patients (n = 47) received 162 MCCPs. Seventy-four percent of parents (n = 35) reviewed MCCPs online. Forty-six percent of these parents (n = 16) sent a follow-up message, and the care team responded within 8 hours (median time = 7.2 hours). In interviews, parents identified MCCPs as an important reference and communication tool. MCCPs for CMC in a complex care program were feasible, facilitated parental engagement, and delivered timely communication.