The potential of households’ used cooking oil (UCO) recycling for biodiesel production is massive. This study aims to promote the shift from UCO inappropriate disposal to sustainable recycling. UCO is classified as municipal waste under the code 20 01 25 (edible oils and fats), according to the European Waste Catalogue. Inappropriate UCO disposal increases the operating cost of wastewater treatment, the risk of groundwater contamination, as well as the greenhouse gas emissions that are associated with its biodegradation. Recycling UCO-to-biodiesel offers a sustainable solution in the exploitation of a problematic waste and its transformation into an energy resource, thus contributing to the reduction of environmental pollution and fossil fuel dependence. This paper includes critical recommendations in order to overcome bottlenecks to successfully promote the UCO-to-biodiesel chain. Quality control of the biodiesel—produced exclusively from UCO—was performed according to the European Standard EN 14214 and the results are presented in the paper. The analysis studies the outcomes from four Southern European countries (Spain, Portugal, Italy, and Greece), which hold the top four places in annual per capita olive oil consumption in the European Union (EU).