The current study investigates the use of lexical bundles in L2 academic writing and L2 learners’ awareness of academic registers. Employing both quantitative and qualitative analyses, all four-word lexical bundles identified from Korean EFL students’ corpora by two different proficiency groups (KEF 1, KEFL2), and native students’ corpus (LOCNESS) were analyzed by VP-, NP-, and PP-based categories using a text analysis tool, AntConc 3.4.4. Although the percentages of VP-based bundles dropped as English proficiency increased, the strong preference for VP-based bundles across the corpora may be attributed to academic expertise rather than nativeness or English proficiency. It also seems to be closely related to L2 students’ prominent dependence on the “You or I + lexical VP” frame with a typical pattern to give their personal opinions using double 1<SUP>st</SUP> person pronouns (e.g. in my opinion, I think). The frequent use of fixed frames such as “anticipatory it” constructions and existential “there” constructions with a lot of/lots of/many implies that L2 learners are in an ongoing process of raising awareness on academic formulaic expressions while trying mixture features of formal and colloquial registers at the same time. As markers of formulaic competence to develop appropriateness and fluency in L2 academic prose, academic bundles seem to be required from early stages of academic writing to raise L2 learners’ awareness of academic registers. Finally, this study suggests instruction based on academic bundles and using concordance data as authentic examples in academic writing courses at all proficiency levels.