Learning English as a Foreign Language (EFL) is a lengthy, demanding, and challenging process, which requires learners' L2 grit relating to their perseverance of effort and consistency of interest. Motivated by the growing body of research on L2 grit over the past few years, this study examined the role of perceived teacher support and learning enjoyment as two important learner external and internal factors, respectively, in promoting EFL learners' L2 grit. The participants were 339 EFL learners selected by multi-stage cluster sampling. The results of SEM indicated that perceived teacher support directly and positively predicted L2 grit, which clearly highlights the role of teachers as an essential element of any language learning situation in motivating and supporting students to exert considerable effort in their learning process and enhance their interest, enthusiasm, persistence, and effort. Additionally, learning enjoyment played a mediating role in the association between perceived teacher support and L2 grit, which indicates its potential for promoting learners' cognitive resources and fostering their continued effort and sustained interest in the lengthy and demanding process of L2 learning. Finally, implications relating to the role of teachers in enhancing learners' enjoyment and grit are presented.