We have performed a joint study of magnetization and magnetoresistance in the antiferromagnetic (AFM) semimetal NdSb under pulsed high magnetic field up to 60 T. We show that NdSb displays extremely large magnetoresistance (XMR), reaching values of 1.77x10(6)% at 1.3 K and 60 T without any sign of saturation. The field-dependent magnetization at 4.2 K reveals a field-induced metamagnetic transition from the AFM to the ferromagnetic state around 9 T. During the metamagnetic transition, a steplike reduction of resistance occurs, resembling the giant magnetoresistance (GMR) behavior in metallic multilayers. The investigation of the Shubnikov-de Haas effect in NdSb suggests that a particular orbital texture might contribute to the XMR effect in addition to the perfect electron-hole compensation.