The personal learning environment (PLE) is a relatively new, learner-centred pedagogical approach using technology for learning. However, empirical research on PLEs remains in its infancy, especially in EFL contexts. This study therefore aimed to explore the effects of a PLE, designed by the researcher, on Vietnamese EFL undergraduates’ speaking skills and examine how these effects varied across different speaking proficiency levels. Forty students at a university in Vietnam participated in a research project lasting eight weeks utilizing the PLE for an English speaking course. Adopting a mixed-methods, quasi-experimental design, this research employed pre- and post-speaking tests, reflective journals, and semi-structured interviews to collect data. Data were analyzed using paired-samples t-tests, one-way ANOVA, and thematic analysis. The results revealed that the PLE enhanced students’ English speaking skills significantly. In addition, this enhancement varied across speaking proficiency groups, with the medium-level group experiencing the most considerable progress, followed by the low-and high-level groups. Qualitative findings from reflective journals and interviews highlighted students’ positive perceptions of using the PLE to enhance their speaking skills. In short, this research underscores the potential of using the PLE approach in developing students’ English proficiency and provides insights for educators and policymakers to employ autonomous language learning pedagogies.