Despite previous research on the use of the first-person pronoun in academic writing, it has rarely been studied in L2 writing and learner corpus research. In this study, the pronoun I was analyzed and compared between native speaking (NS) and Korean nonnative speaking (NNS) corpora of English argumentative writing samples. To identify differences in its discourse functions, three categories (essay commentator, experience provider and opinion provider) were formulated. The findings show that the normalized frequency of the pronoun was higher in the learner corpus. However, the pronoun occurred less frequently within individual essays but was found in more essays. Unlike the NS corpus, the opinion provider occurs more frequently than the experience provider in the learner corpus. For the opinion provider, Korean students usually selected the verb think. The present study suggests the need to develop students’ awareness of the discursive usage of the pronoun and expand their repertoire of metadiscursive devices.