To understand the climate impact of the wildfires, it is essential to monitor the aerosol emissions from biomass burning and to estimate their optical properties and radiative forcing. This study analyzed wildfires in Brazil, Angola, Australia, California, Siberia, and South‐east Asia that occurred after 2018 using data obtained with the Second‐generation GLobal Imager (SGLI) onboard GCOM‐C which ... [Show full abstract] is a polar‐orbit satellite launched by JAXA on 23 December 2017. We showed the SGLI‐based four‐year variation of the aerosol optical properties, Aerosol Optical Thickness, Ångström Exponent (AE), and Single Scattering Albedo (SSA) for each region complemented with other satellite‐ and ground‐based data. From the SSA and AE relationship analyses, we confirmed that their optical properties depend on the relative humidity and type of burned vegetation, which is consistent with the previous studies. Moreover, we estimated the net incoming radiation at the top of the atmosphere during the intense fire periods to understand the impact of the direct effect of biomass burning aerosols on radiative forcing. The estimates show a significant negative radiative forcing (i.e., a cooling effect) over the ocean (−78 and −96 Wm ⁻² in Australia and California, respectively). In contrast, small values are observed over land ( ∼ − 10 Wm ⁻² for all six regions). Therefore, taking the regional characteristics of the optical properties and surface reflectance into account is necessary to estimate the effect on radiative forcing and future impacts of a short‐lived climate forcer from wildfires.