This study explores the relationship between motivation, classroom engagement, and speaking proficiency among Iranian English as a Foreign Language (EFL) learners. Speaking skills are essential for language acquisition, yet Iranian students often face challenges in effective oral communication. Using a quantitative, cross-sectional approach, the research sampled 120 intermediate-level EFL students aged 15–18, divided into three proficiency groups (A2, B1, B2) based on the Common European Framework of Reference for Languages (CEFR; Council of Europe, 2001). Data were collected through a motivation questionnaire (Dörnyei, 2005), classroom participation scores, and a standardized speaking rubric (Brown, 2007). The analysis revealed significant positive correlations between motivation, engagement, and speaking performance, with higher motivation (r = .362, p < .001) and greater classroom involvement (r = .319, p < .001) linked to better speaking outcomes. Proficiency level was crucial, with B2 learners outperforming B1 and A2 peers (p < .001). A multiple regression analysis indicated that motivation, participation, and proficiency explained 51% of the variance in speaking performance (R² = .51, p < .001). These findings underscore the importance of motivation and active engagement in improving speaking skills, supporting the use of tailored communicative, task-based strategies and highlighting the need for differentiated teaching approaches.