This study explored the effectiveness of task-based language teaching in improving students’ speaking skill ability and their perceptions of task-based language learning in the case of Gasay Preparatory School. The objective of this study was to investigate the effect of TBLT on students’ speaking skill ability and their perception towards TBLL of grade 11 students. The research methodology of this research is an experimental study. The study employed quasi-experimental design as experimental and control group. In this research, the intact groups were selected from eight sections grade 11 students by using non-probable sampling technique of convenience sampling method. The researcher selected section G 54, students, among these, 24 for experimental and 30 for control group for the study by using convenience sampling. A task based language teaching manual was developed by the researcher for the experimental. The relevant quantitative data was gathered through two instruments, those are tests and questionnaires. Tests and questionnaires were used in this research: pre-post-test of speaking skills to measure the effects of task-based language teaching on students’ speaking skill ability. The tests covered the dimensions of fluency and accuracy. An attitudinal questionnaire aimed at investigating the experimental students’ perception before and after treatment. Independent samples t-test and paired samples t-test were used to analyze the quantitative data. The findings indicated that, the TBLT program significantly increased the students’ speaking skill ability of the experimental group after treatment. Moreover, the TBLT program has a significant effect on students’ perception towards task-based language teaching and learning. The result of this study may inspire teachers in teaching speaking to adapt some of the activities in the usual course book according to a more task approach, so that students can participate in oral practice of language activities and in turn help them improve their speaking abilities. Key words: Tasks, Task-based language teaching, Perception