The COVID-19 pandemic has altered all aspects of human life since its breakout in March 2020 in the USA and around the world. There has been a tremendous increase in the use of plastic products as most of the PPE (masks, gloves, and other medical equipment) are made from plastic. Therefore, the generation of plastic waste was expected to increase significantly, which was also reported by many news agencies and organizations. This study determines the increase in plastic waste in municipal solid waste (MSW) and investigates its effect on landfill volume consumption during the COVID-19 pandemic. MSW samples were collected from the working face of Irving Hunter Ferrell landfill from May 2020 to December 2020. During every attempted sample collection, eight bags of MSW samples, each weighing 20–25 lbs., were collected. The MSW samples collected from the landfill were characterized and later the volume was estimated to evaluate the potential effects on landfill airspace. Based on the experimental investigations, it was found that plastic waste generation increased significantly during the pandemic (increasing from an 18.5% pre-pandemic level to 30% during the pandemic). Volumetric estimation suggests that the increased amount of plastic waste occupies 20% more volume in landfills. Quantification and estimation of the volume of the increased amount of plastic waste can be useful in predicting the impact of the pandemic on the lifetime of landfills.