Mesoporous ferrierite zeolite (FER) synthesized by a post-desilication method was applied for a gas-phase dimethyl ether (DME) carbonylation to confirm the contributions of the newly formed mesoporous structures above 10 nm in size. The distribution of surface acidic sites and extent of coke deposition was significantly altered, resulting in showing different catalytic activity and stability, which were mainly caused by the post-synthesized larger mesopores on the FER. The newly formed mesoporous structures in the range of 5-40 nm on the pristine seed-derived FER (SFER) with a Si/Al molar ratio of 10.4 were largely changed by a desilication/recrystallization duration, and the mesopores significantly increased the surface acidic sites with similar extent of crystallinity even with a lower Si/Al ratio of 6.7-8.6. The increased strong acidic sites corresponding to Brønsted acid sites after an optimal desilication duration for ~3 h on the mesoporous SFER (m-SFER(3)) were mainly responsible for an increased DME carbonylation activity with smaller formation of coke precursors due to facile mass transport phenomena through its lager mesopores.