This study attempted to investigate the effect of flipped language learning through mobile devices on Iranian EFL learners’ grammar learning, their motivation for learning the foreign language, and their belief toward language learning. To this end, a quasi-experimental research with the pretest-posttest control group was used with a sample of 60 learners from one of the high schools of Qorveh, Kordestan, Iran. The instruments used in the current study were Oxford Quick Placement Test (OQPT), a pretest and posttest in grammar, The Foreign Language Learning Motivation questionnaire designed and validated by Gonzales (2006), and Beliefs Toward Language Learning postulated by Peralta Castro and Andrade-Arechiga Mail (2017). The results of independent samples t-tests and Mann-Whitney U tests revealed that the flipped learning improved the grammar performance of the students. Furthermore, the levels of L2 motivation and belief toward language learning changed after the treatment. The study has implications for EFL teachers and learners in using flipped language learning through mobile devices in English classes in general and teaching L2 grammar in particular. The conclusions of this study can also aid course designers.