Methane (CH₄) emissions from landfills are a major contributor to global greenhouse gas (GHG) emissions due to methane’s significantly higher global warming potential (GWP) compared to carbon dioxide. Accurate quantification of landfill methane emissions is essential for effective climate policies, regulatory compliance, and informed decision-making in waste management. However, existing estimation methods—primarily based on single-time satellite observations—often lead to inaccuracies due to their inability to capture temporal variations in emissions. This paper presents a novel hybrid methodology that integrates high-resolution satellite-based methane detection with complementary on-ground measurements to improve landfill methane emission estimates. Satellite observations, conducted 12 to 24 times annually, capture seasonal variations, while on-ground tracer gas correlation measurements—performed multiple times per day, including nighttime—help refine daily emission profiles. By leveraging these combined datasets, our approach provides a more robust annual emission estimate compared to traditional extrapolation methods. This methodology was developed during a six-month European Space Agency (ESA) Kickstart-funded study, where preliminary results demonstrated its potential to reduce uncertainties in landfill methane emissions. A full-scale validation study is planned for 2026 on selected European landfills. The findings of this study could significantly enhance emission reporting accuracy, support regulatory enforcement, and drive a transition towards lower-GHG waste management alternatives.