The COVID-19 global health crisis has resulted in the emergence of a new type of solid waste–inappropriately discarded disposable masks (DMs)–posing serious risks to the public health and to the environment. This study assessed the knowledge-(“K”) and self-reported practices-(“P”) of the general public in DM waste management. A researcher-developed instrument was utilized to gather data with a reliability coefficient index of 0.94. The survey was participated in by 13,116 online users. Pearson r and multiple linear regression were performed to test the relationship between the participants’ demographic characteristics and their K and P. Results revealed that the participants obtained a weighted mean and standard deviation of 1.15±0.10, which shows that 11,597 or 88.41% are knowledgeable on solid waste disposal and management. The self-reported practices of the participants obtained weighted mean and standard deviation rating of 2.16±0.10, which is interpreted as “Always Practiced”. This signifies that the participants adequately practiced the essentials in disposing DMs. Furthermore, there is a significant relationship between K and P with their demographic characteristics on disposing DMs like age, sex, level of education, annual income, and type of residence. The obtained Pearson r =-0.178 ( p <.01) indicates that the level of knowledge of the participants is significantly related to the practices they apply in disposing used DMs. As a recommendation, campaigns and interventions on the proper disposal of DMs should be put forward and implemented, utilizing various social media resources and platforms that are conveniently accessible to the general public.