Biblical scholars dispute the meaning and function of ἐγώ εἰμι uttered by Jesus in John 8:24 and 8:28. This paper proposes a linguistic method that provides a framework to assess the linguistic features of the New Testament text and that may offer new insights into the Johannine ἐγώ εἰμι clauses. By adopting the theory of Systemic Functional Linguistics (SFL), this paper conducts a register analysis of ἐγώ εἰμι in John 8:24 and 8:28, with reference to Isa 43:10 and 43:25. Based on this analysis, the paper argues that ἐγώ εἰμι uttered by Jesus in John 8:24 and 8:28 is used intentionally as an allusion to the divine name in the Old Testament, which specifically and powerfully invokes the image of God, and that this wording therefore functions to portray Jesus’ divinity.