N,N′‐Dimethylated 6‐(benzyloxy)‐1,3,5‐triazine‐2,4(1H,3H)‐dione (DMBOT) has been developed as a triazinedione‐based, stable solid reagent for acid‐catalyzed O‐benzylation. The conceptual basis of the design was to fix the core triazinedione skeleton, and the two methyl groups in positions 1 and 3 were introduced to acheive this. The coproduct of DMBOT can be easily removed by simple washing. Various acid‐ and base‐labile alcohols were O‐benzylated by using DMBOT in the presence of an acid catalyst. In particular, 2,6‐di‐tert‐butylpyridinium trifluoromethanesulfonate, which is a mild, stable, and nonhygroscopic acid catalyst, can be used with DMBOT for this reaction. Compared to other reported methods, DMBOT gave better results for several challenging O‐benzylation reactions under nonbasic conditions.