It is meaningful to develop a high-performance optic bending sensor characterized by effective direction judgment, compact length, and high sensitivity. In this Letter, a compact Mach–Zehnder interferometer (MZI) fiber sensor for vector bending measurement is proposed and investigated. This sensor is prepared by off-axis splicing seven-core fibers (SCFs) and multi-mode fibers (MMFs) with different core diameters, which achieves a compact sensing length of 8 mm. The chirped core fiber structure excites the high-order cladding mode in the interference component, which enhances the sensing sensitivity. Experimental results indicate that the maximum bending sensitivity of the sensor is -230 nm/m^-1. Moreover, the three bending directions of the sensor can be distinguished by judging the variations of the two interference dips during the measuring process. The proposed method and thought can provide some operating experience and principles for the all-fiber curvature sensor design.