The martensitic transition, magnetocaloric effect (MCE) and shape memory effect (MSE) of ferromagnetic Heusler alloys Ni 50 Mn 50−x Sb x (x = 12, 13 and 14) have been investigated. A large positive magnetic entropy change S M was observed in the vicinity of the martensitic transition. The maximum value of S M is 9.1 J kg −1 K −1 in Ni 50 Mn 37 Sb 13 at 287 K for a magnetic field change of 5 T. This change originates from the first-order transition from a low-temperature weak-magnetic martensitic phase to a high-temperature ferromagnetic parent phase. A magnetic-field-induced shape recovery strain of about 15 ppm at room temperature and at a relatively low magnetic field (1.2 T) was observed to accompany the reverse martensitic transformation. The large field-induced MCE and MSE in the NiMnSb system make it a promising material for room-temperature application.