This study analyzed the problems faced by the assembly line of an automotive manufacturing company, which recorded an increase in the company’s production cost each month. The increasing production cost incurred because the company could not satisfy the production volume target set by the production planning department. Hence, the workers needed to do extra work to achieve the goal that led to additional production costs and loss of sales. Therefore, the objective of this study is to propose a new assembly plant layout to minimize the average waiting time and average total processing time in the system and maximize the total number of completed jobs. A Discrete Event Simulation (DES) model is used as a planning tool for solving the problem under study. The performance of the proposed assembly plant layout is compared with the existing assembly plant layout using Arena software. The average waiting time, average total processing time in the system and the total number of completed jobs that will contribute to overall production costs used as performance measures. The proposed assembly plant layout shows that the average waiting time decreased by 60.61 %. The average total processing time in the system decreased by 35.12 %. The total number of completed jobs has increased by 11.23 % as compared with the current assembly plant layout. Hence the new proposed assembly plant layout is recommended.