•A novel Mach–Zehnder Interferometer (MZI) formed by cascading two vase-shaped tapers in a single mode fiber (SMF) is proposed in this work. The vase-shaped taper is fabricated by fusion splicing a fiber sphere with a fiber tip under strong arc discharge.•The curvature sensing characteristic of the proposed vase-shaped taper-based MZI is experimentally investigated, displaying that the interference spectrum has a blue shift with the increase of applied curvature. The sensor realizes a large range measurement of curvature from 0.9284m−1 to 4.0470m−1 with sensitivities of −8.41nm/m−1 and −16.72nm/m−1 in the curvature range of 0.9284m−1 to 2.4564m−1 and 2.6025m−1 to 4.0470m−1, respectively. It also shows a low temperature-curvature cross-sensitivity of −0.0016m−1/°C and −0.00082m−1/°C in the two measurement ranges, which are lower than the corresponding curvature resolutions that are 0.0024m−1 and 0.0012m−1.•The proposed sensor exhibits the advantages of low cost, negligible temperature cross-sensitivity, fine curvature sensitivity and large measurement scale. A novel Mach–Zehnder Interferometer (MZI) formed by cascading two vase-shaped tapers in a single mode fiber (SMF) is proposed in this work. The vase-shaped taper is fabricated by fusion splicing a fiber sphere with a fiber tip by applying strong arc discharge. The curvature sensing characteristic of the proposed vase-shaped taper-based MZI is experimentally investigated, displaying that the interference spectrum has a blue shift with the increase of applied curvature. The sensor realizes a large range measurement of curvature from 0.9284m−1 to 4.0470m−1 with sensitivities of −8.41nm/m−1 and −16.72nm/m−1 in the curvature range of 0.9284m−1 to 2.4564m−1 and 2.6025m−1 to 4.0470m−1, respectively. Its temperature-curvature cross-sensitivities are −0.0021m−1/°C and −0.0011m−1/°C in the two measurement ranges, which are lower than the corresponding curvature resolutions which are 0.0024m−1 and 0.0012m−1. The proposed sensor exhibits the advantages of low cost, negligible temperature cross-sensitivity, fine curvature sensitivity and large measurement scale.