The rapid expansion of rubber cultivation constitutes a significant land-use change in Southeast Asia. Despite fertilization being a common practice in rubber plantations, its impact on soil methane (CH₄) dynamics has remained poorly understood. Our study demonstrates that fertilization not only reduces soil CH₄ consumption but also increases CH₄ production, transforming rubber plantations from a net CH₄ sink to a source. Implementing rational fertilization could enhance atmospheric CH₄ removal.