Lactic acid is a versatile chemical with a wide range of industrial applications, including food additives as well as the production of biodegradable plastics, pharmaceuticals and cosmetics. LA can be produced through carbohydrate fermentation using various microorganisms, including lactic acid bacteria (LAB). However, the high production cost of commercial fermentation media for lactic acid raises concerns among researchers. Consequently, there is a demand for research to develop new, more affordable, and sustainable fermentation media. Utilizing underutilized agro-industrial wastes from Malaysia, particularly in the coconut, oil palm, rice, and sugarcane processing industries, offers several advantages. These include biomass reuse, cost-effective production of valuable chemicals, and agricultural waste reduction. This review discusses the potential of underutilized Malaysian agro-industrial waste from the coconut, oil palm, rice and sugarcane processing industries as sustainable carbon sources for LA production. The topics covered encompass the chemical and nutritional composition of the wastes, their potential for lactic acid fermentation with specific microorganisms, factors influencing lactic acid production, and potential applications. Additionally, this review also highlights the challenges and opportunities associated with reutilizing agricultural waste for lactic acid production.