This study examines the use of English prepositions among Korean EFL learners, focusing on their frequency, variety, and functional patterns in comparison to native English speakers. Using data from the Yonsei English Learner Corpus and the Louvain Corpus of Native English Essays, the analysis reveals that while Korean learners demonstrate increased preposition usage with higher proficiency, their overall usage remains less frequent and less diverse than that of native speakers. Specifically, relational prepositions such as of are underused, whereas setting prepositions such as in are more common but exhibit a limited functional range. Drawing on Markedness Theory, the study indicates that learners tend to favor unmarked, prototypical prepositions while avoiding more marked, contextually complex forms. This finding suggests that markedness influences both the selection and functional range of prepositions in learner output. Based on these findings, the study recommends pedagogical strategies that integrate explicit instruction with implicit approaches, including incidental learning, to help learners develop a more intuitive understanding of prepositional use. The study concludes by highlighting the importance of instructional methods that address both foundational and advanced prepositional functions, enabling learners to effectively navigate the complexities of English prepositions.