The mitigation of methane (CH₄) emissions from livestock production is crucial to China’s carbon neutrality. Here we established a high-spatiotemporal-resolution dataset of the country’s livestock CH₄ emissions from 1990 to 2020 using four large-scale national livestock greenhouse gas inventory surveys. We estimate CH₄ emissions to be 14.1 ± 2.0 Mt in 2020 and to increase by 13% until 2030 despite CH₄ intensity per kg animal protein having decreased by 55% in the past 30 years. Approximately half of the emissions come from 13% of all Chinese counties. The technical CH₄ mitigation potential is projected to be 36 ± 8% (4.4–6.9 Mt CH₄) in 2030, and reducing food loss and waste could mitigate an additional 1.6 Mt of CH₄. Overall, most CH₄ mitigation could be achieved by increasing animal productivity and coverage of lagoon storage at carbon prices below US$100 tCO₂e⁻¹, being more cost-effective than livestock nitrous oxide mitigation in China.