Lean is the concept of boosting an organization's speed and efficiency by removing waste. On the other hand, Six Sigma is a continuous improvement approach recommended to eliminate variability. This article presents a comprehensive review of integration of Lean Six Sigma (LSS) for process and service improvements across various facilities and industries. By synthesizing literature, this review study explores the potential benefits and effectiveness of combined Lean-Six sigma. It highlights their complementary strengths Lean’s emphasis on waste reduction and flow efficiency, and Six Sigma’s focus on reducing process variability and improving quality. The review demonstrates that LSS has evolved into a strategic framework applicable not only to manufacturing but also to healthcare, education, and public services. Key findings reveal that when implemented effectively, LSS leads to enhanced operational efficiency, customer satisfaction, cost savings, and quality outcomes. The study concludes that Lean Six Sigma, supported by leadership commitment and cultural adaptation, offers a powerful toolkit for continuous improvement in diverse operational contexts.