Biochar (BC) application to agricultural soil has been proposed as an effective countermeasure to mitigate climate change. A laboratory incubation experiment was carried out to gain insight into the effectiveness of BC on methane (CH4) consumption in a tropical clayey vertisol. Except for the control treatment, BC of two different sizes (<0.25 or 0.25–2.00 mm) was mixed with vermicompost (VC), poultry manure (PM) or farmyard manure (FYM). BC and organic amendment were added to soil at 10% w/w and 80 kg N/ha, respectively. BC increased CH4 consumption rate, k, in soil, irrespective of organic amendment type. The CH4 consumption potential of soil was greater with the smaller size BC (<0.25 mm). Of the three organic amendments, VC exhibited the highest k (0.105) followed by FYM (0.093) and PM (0.072). BC (<0.25 mm) + PM was the most effective of the organic amendments in enhancing CH4 consumption (k = 0.242). The lag phase varied between 7.3 day (control) and 1.0 day (soil + VC). Results revealed that there was a significant (P < 0.0001) effect of organic amendment and BC on CH4 consumption, CO2 production and microbial abundance. Cumulative CO2 production (mg/g soil) varied between 2.15 (control) and 8.77 (soil + PM + BC < 0.25 mm). Pearson's correlation analysis showed significant correlation between CH4 consumption and methanotrophs abundance (P < 0.001). The study shows that BC enhanced CH4 consumption potential in agricultural land on a tropical vertisol, particularly using the smaller size (<0.25 mm), and could be an effective strategy to mitigate atmospheric CH4.