The presence of mobile technologies within preschool and elementary classrooms has been increasing, yet review studies which measure the effectiveness of mobile technologies to support children's literacy achievement remains scarce. The purpose of this study is to conduct a systematic review to examine the influence of mobile technologies on pre-kindergarten-5th grade students' literacy achievement between 2007 and 2019. Findings are reported according to study characteristics, followed by the patterns and trends related to achievement within and across literacy domains (phonics, phonemic awareness, fluency, vocabulary, comprehension, writing). We provide mobile device and app use strategies for teachers, while mapping clear research pathways for educational researchers and digital designers, with the ultimate goal of advancing the use of mobile technology to improve children's literacy achievement.