In the current national curriculum, communicative competence in English as a subject in basic education (ESBE), is explicitly included among the ten core competencies, positioning English communication as part of the state's definition of a “Literate Thai” citizen—a citizen who possesses not only foundational literacy and numeracy, but also the communicative skills needed to participate effectively in a globalized society. Although scholars have repeatedly stressed that English as a Foreign Language (EFL) learners in Thailand need stronger communicative English abilities, empirical insights into how competency-based teaching and learning (CBTL) is interpreted, implemented, and enacted by ESBE teachers remains scarce, especially in less resourced parts of the country. To address this void, our study employed key stakeholders' interviews to assess the implementation of CBTL across three private schools in Narathiwat located in Thailand's three southern border provinces (collectively known as “the Deep South”). This study highlights the role of school-level structures operating at both micro- and macro-organizational scales. Findings reveal that the schools' shift from a content-driven to a competency-driven English curriculum hinged on policy implementation at the school level, integration of communicative English skills across various subjects, influence of sociocultural and linguistic contexts, and inclusive stakeholders' engagement. The study suggests practical pedagogical implications regarding the 4C's: communication, community, culture, and connection with other learning areas and subject disciplines, which can strengthen CBTL of ESBE for teachers and students within Thailand's Deep South and similar contexts.