This article proposes a frequency switchable microwave resonator based on a microfluidic defected ground structure (m‐DGS) that provides wider frequency tuning ratio. Because its resonant frequency is determined from the DGS geometry, the resonant frequency can be switched by injecting EGaIn liquid metal into the m‐DGS to decrease the effective inductance and hence increase resonant frequency to 7.7 GHz from 3 GHz, that is, 88% tuning range. The proposed idea is demonstrated numerically and experimentally.