The increasing reliance on online English as a Foreign Language (EFL) education has renewed scholarly interest in understanding how learners can sustain effective engagement and achievement in digitally mediated learning environments. Central to this discussion is selfregulated learning (SRL), which enables learners to plan, monitor, and adapt their learning processes in response to contextual demands. Drawing on an interdisciplinary body of literature from second language acquisition, positive psychology, and sustainability-oriented education, this review synthesizes research on the roles of foreign language enjoyment and L2 grit as key psychological resources supporting SRL in online EFL contexts. The literature suggests that foreign language enjoyment fosters learners’ emotional engagement, cognitive flexibility, and willingness to participate, all of which are essential for sustaining self-regulatory behaviors in online settings. Similarly, L2 grit, conceptualized as perseverance and sustained interest in language learning, is frequently associated with learners’ capacity to cope with challenges, maintain effort, and persist in long-term learning goals. When considered together, enjoyment and grit offer complementary pathways through which affective and motivational dimensions interact to support autonomous and resilient learning. From a sustainability perspective, this review argues that SRL, supported by positive emotional experiences and perseverance, contributes to enduring learning practices that extend beyond immediate instructional outcomes. By integrating insights across disciplines, the paper highlights the importance of designing online EFL environments that nurture enjoyment and grit as foundations for sustainable, learner-centered education. The review concludes by outlining pedagogical directions for educators and policymakers seeking to transform online language education through psychologically informed and sustainability-aligned approaches.