Over the past few decades, the lean manufacturing (LM) approach has gained strong recognition as one of the foremost strategies for enhancing organizational performance. The ready-made garments (RMG) sector of Bangladesh is the most vital economic sector, which is under the threat of acute competition. This sector has been claiming to have practicing lean manufacturing to some extent about two decades to overcome its low productivity issues, but the resulting success of its implementation is far cry. In this context of reality, the sector needs proper attention and effective guidelines to implement lean manufacturing successfully to enhance not only productivity but the overall performance in all pertinent dimensions to remain competitive. The main purpose of this research is to construct a conceptual framework by consolidating all the major characteristics applicable therein with its clear dimensions for successful LM implementation in the RMG sector of Bangladesh. This study is based on an extensive and comprehensive literature review of the various aspects of LM implementation, especially focused on the critical success factors (CSFs), lean implementation activities, organizational performance and the linkages between them. The conceptual framework presented here illustrates how the CSFs positively influence lean manufacturing implementation activities, which ultimately contribute to achieving excellence in organizational performance. This is an attempt to guide RMG factories on what CSFs are to be considered and what tools are to be used to sustain the rigors real LM implementation for wider and improved organizational performance. This paper, therefore, identified the genuine need for a conceptual framework for the successful lean manufacturing implementation in the aforesaid sector.