The COVID pandemic has prompted people to adopt new facemask usage habits, which has led to an increase in the waste generated following facemask disposal. Recycling could be considered as a way to minimize facemask waste's adverse environmental impact because of its polymeric component. In this study, the recycling of face mask waste was carried out using injection molding to create a commercial door knob product. The experiment performed using Taguchi L4 orthogonal array was used to optimize injection molding parameters of the barrel and molding temperature as well as the inclusion of the ear loop part. Analysis of variance (ANOVA) ascertains the percent contributions to have minimal shrinkage and maximum product weight. Finally, grey relational analysis (GRA) was performed to obtain optimal parameters in multi-objective optimization. The optimal parameter combination was raised to ensure the successful recycling of waste facemasks into a commercial product.