The present study seeks to find the students' performance towards the assigned tasks related to cartoons and their perceptions towards the use of it as an authentic, supplementary teaching tool to facilitate the process of speaking. A sample of thirty-five students was selected to involve in different tasks related to selected number of cartoons. The researcher conducted an empirical investigation by employing quantitative and qualitative research methods. Audio recordings and classroom observations were used to investigate the students' active involvement towards the assigned tasks related to cartoons and a well-structured questionnaire was employed to evaluate their perceptions towards the use of it as an authentic supplementary tool in teaching the speaking skills of ESL learners. The results of the study revealed that a majority of students actively involved in the assigned task related to cartoons. The students gave a comprehensive and controversial account of the assigned cartoons incorporating the clues given by the facilitator resulting to assure better learner motivation and participation, transforming the teaching and learning experience into an enjoyable, stimulating, and memorable experience. Furthermore, nearly 70% of students demonstrated a positive perception towards the use of cartoons in ESL classrooms as they believed it facilitates their speaking skills making the input more comprehensible and enhancing collaborative learning. Besides, they accepted that cartoons improve students' personal relationships with fellow students and promote peer learning. Based on the findings, it was concluded that cartoons can be effectively used as an authentic supplementary tool in ESL classrooms to teach speaking skills to Sri Lankan ESL learners.