The invention is a sharpener for a knife of a food slicer. The sharpener includes a base assembly and a sharpener assembly. The base assembly includes a lever mounted thereto on a pivot; the lever carrying a cam member which extends therefrom. The sharpener assembly includes a housing and a longitudinal cavity, a sharpening wheel mounted for rotation on an axle which reciprocates lengthwise in the cavity, a compression spring positioned in the cavity at the base of the axle, and an actuator which reciprocates in the cavity portion on the side of the spring opposite the axle. Upon moving the lever about its pivot, the cam contacts the actuator and moves the actuator in the direction of the axle and compresses the spring. The spring moves the plunger lengthwise within the cavity and urges the sharpening wheel against the knife.