The transesterification of waste cooking palm oil (WCPO) and palm oil (PO) with methanol to fatty acid methyl ester (FAME) was studied using CsM-SiO2 as a heterogeneous catalyst. The catalyst was prepared by an impregnation method with 10%–30% CsO2 loaded onto silica. The catalyst with 25% loading achieved the highest FAME content. The effects of catalyst on transesterification reaction parameters to FAME content were investigated. The FAME content reached 90% at 65 °C in 3 h with 3 wt.% catalyst loading and 20:1 molar ratio of methanol to oil for WCPO transesterification and 89% with 2 wt.% catalysts loading for PO transesterification, respectively. The solid catalyst can be reused for four batch cycles without significant deactivation. Also, the catalyst exhibited good tolerance toward 1 wt. % water content in WCPO feedstock, without significant changes in the FAME content.