This study explored the effectiveness of integrating peer assessment (PA) and non-scripted role-play (NSRP) activities in enhancing the oral performance of Thai EFL high school students. Conducted at a public secondary school in Bangkok, the research involved 31 Grade 12 students and utilized a mixed methods approach. Over nine weeks within the "Research Methods and Presentation Skills" course, the intervention included training sessions, a speaking rubric, an attitude questionnaire, and semi-structured interviews. Data analysis encompassed quantitative methods like t-tests and qualitative methods such as thematic analysis. The findings demonstrated that PA and NSRP activities significantly enhanced oral performance by fostering speaking skills, cultural competence, and self-awareness. NSRP activities improved speaking complexity, accuracy, and fluency through real-life communication scenarios, enhancing motivation via authentic interactions. PA complemented NSRP by promoting collaborative learning, self-reflection, and critical self-evaluation. Pedagogically, effective implementation of PA and NSRP aligned with communicative language teaching principles integrated digital literacy, and accommodated learner diversity.