A valve body for a fluid injector includes a central longitudinal axis and a one-piece base body. The base body has a side wall defining a recess extending from a fluid inlet side to a fluid outlet side of the base body. The side wall has a thin portion having a decreased wall thickness relative to further portions of the side wall that adjoin the thin portion along the longitudinal direction towards the fluid inlet side and the fluid outlet side. The valve body includes a metallic reinforcement jacket that is rigidly coupled to the base body and which axially overlaps the thin portion having the decreased wall thickness.