Landfilling is the predominant method for municipal solid waste management in many regions. A large amount of disposable face mask waste is generated and disposed in landfills. In this study, we explored the change of disposable masks in landfills through simulated processes, encompassing the exposure to sunlight before burial and contact with landfill leachate. After the exposure to UV radiation, the masks’ three layers exhibited surface abrasions and fractures, indicating an aging process that rendered them unstable. Chemical alterations in the masks and a reduction in mechanical strength were observed after UV weathering, providing evidence of the aging phenomenon. In addition, the physicochemical properties of disposable face masks before and after aging in landfill leachate were further investigated. It was found that the aging of these masks were accelerated in landfill leachate, resulting in the release of elevated quantity of microparticles, surpassing those released in deionized water after UV radiation and aging. Specifically, after 48 h of UV radiation, the concentration of released particles in leachate rose 7.5 times after 30 days of aging. Disposable mask end-life profiling such as this study shed light on the development of new strategies of waste management and further sustainable product development.