This study investigates how Filipino English teachers (FETs) construct professional identity within South Korea’s private academies, or hagwons. While prior research on non-native English-speaking teachers (NNESTs) has focused on formal institutions, this study addresses the underexplored commercial ELT sector. Survey and interview data were collected from 20 FETs. Quantitative results showed that adaptation strategies— such as credentialing, accent negotiation, and instructional flexibility—were the strongest predictor of professional identity. Qualitative thematic analysis revealed five core themes: nonlinear job entry, accent negotiation, self-driven credentialing, relational labor, and instructional autonomy. Despite limited institutional support, participants asserted legitimacy through relational work and pedagogical agency. These findings highlight how FETs negotiate identity in stratified, native-speakerist environments and contribute to broader discussions on NNEST legitimacy, World Englishes, and ELT equity. The study calls for inclusive policies that recognize diverse teacher identities beyond Inner Circle norms.