As a popular alternative fuel, biodiesel (BD) has gained the attention of many. Cost related to the oil feedstock may take 60%–70% of total BD production cost. Utilization of waste oils to produce BD potentially lowered that cost and solved problems related to its accumulation in nature. Several technologies to produce BD from waste oils are available today with focus on handling the high free fatty acid and moisture content that come with the waste oils. Evaluation of techno-economic and life-cycle analysis studies were also discussed in this chapter to take the competitiveness and sustainability of BD production from waste oils into consideration.