Although landfill cover soils play an important role in methane (CH₄) oxidation, controls on this process remain poorly understood in capped landfills. This study quantified CH₄ fluxes and environmental controls in vegetated and non-vegetated cover soils across two capped landfill sites in southern Ontario using field measurements and laboratory incubations. From April 2024 to April 2025, 688 CH₄ flux measurements were collected. The strongest CH₄ uptake occurred in late summer to early fall under dry (<10% volumetric moisture content, VMC) and warm (>25 °C) conditions, with fluxes reaching −2.79 mg CH₄ m⁻² d⁻¹. Uptake was minimal in winter and early spring when soils were wetter (23–30% VMC) and colder (<10 °C). Linear mixed-effects models identified soil moisture as the primary driver of CH₄ flux, while soil temperature had a weaker effect and vegetation treatment showed no consistent influence. Incubation experiments showed maximum CH₄ oxidation at 20–40% soil moisture and 25 °C, with peak rates up to 35.4 µg CH₄ g⁻¹ d⁻¹. Oxidation declined at higher moisture (60–80%) and at low (5 °C) or high (35 °C) temperatures. Vegetation treatment did not significantly affect oxidation under controlled conditions. Overall, results highlight soil moisture as the dominant control on CH₄ oxidation by regulating oxygen availability and microbial activity in landfill cover soils. Keywords: methane oxidation, soil moisture, soil temperature, landfill cover soils, incubation experiment