Landfills　emissions,　ranking　as　the　third-largest　anthropogenic　source　of　methane　in　the　atmosphere,　pose　environmental　challenges　and　threaten　public　health.　The　pivotal　role　of　clay　as　a　mitigating　agent　for　methane　emission　within　landfill　cover　systems　cannot　be　overstated;　however,　our　understanding　of　methane　escape　from　fractured　clay　remains　limited.　This　study　aims　to　address　the　existing　gaps　by　proposing　a　robust　analytical　model　of　methane　transport　in　both　fractures　and　clay　matrix.　Our　investigation　also　includes　a　dimensionless　analysis　to　govern　the　relative　significance　of　diffusion　and　advection　in　methane　emission　from　fractured　clay,　systematically　reviewing　factors　such　as　the　degree　of　water　saturation　(Sr)　and　fracture　width.　The　methane　concentration　profiles　in　cracked　clay　demonstrated　escalating　sensitivity　to　Péclet　(Pe)　numbers,　especially　when　advection　dominates　transport.　Our　findings　also　highlight　the　prevalence　of　preferential　methane　flow　with　increasing　Sr　in　the　clay　matrix.　The　flux　of　methane　emission　from　fractures　at　Sr = 0.8　was　130　times　greater　than　that　from　intact　clay.　However,　the　study　necessitates　considering　methane　emission　from　clay　matrix,　particularly　in　dry　clay　conditions　(Sr = 0.2　and　0.4).　The　accumulated　methane　emission　flux　from　intact　clay,　more　than　that　emitted　from　fractures　by　about　2.5　times　at　Sr = 0.2,　was　1.3 × 10−5 g/m/s.　The　findings　significantly　advance　the　understanding　of　gas　transport　in　fractured　geomaterials,　revealing　the　effect　of　water　saturation　and　crack　width　on　methane　emissions　from　fractures.　Overall,　the　outcomes　emphasize　the　inclusion　importance　of　methane　emission　from　cracked　clay　in　the　design　of　gas　barriers.　©　2024　John　Wiley　&　Sons　Ltd.