Mobile learning has extensively influenced students' learning gains and motivation due to the hardware and software development of mobile devices and applications in recent decades. On-the-go learning increases the capacity for flexible and joyful learning and guarantees access to the instructional content anywhere, anytime. Despite their potential benefits, the presence of mobile applications in students' every educational activity can be detrimental to their cognitive abilities as misuse or overuse of specific applications may influence students' concentration and critical thinking. One such downside is reported for overusing automatic spelling correction software, known as AutoCorrect (AC), in language learning. Uncertainty regarding the educational values of AC has increased as students' spelling skills and vocabulary knowledge have declined. The main problem this study addressed is examining the relationship between EFL learners' AC use and their vocabulary size; and if their academic self-regulation mediates this association. Data were gathered from 101 foreign language learners who completed the measures of AC use, academic self-regulation, and vocabulary size. The results showed significant positive correlations between AC use, vocabulary size, and self-regulation. Further, testing the model supported a mediating role for self-regulation in the relationship between AC use and vocabulary size, suggesting that AC use can lead to more knowledge of English words in the condition of deploying self-regulatory strategies. The study signifies how academic self-regulation can assist learners in exploiting mobile learning (m-learning) to their advantage and attaining their educational goals more efficiently.