A fuel injector for fuel ignition systems of internal combustion engines includes a magnetic circuit having a core, a magnetic coil and an armature, and a movable valve needle, which has a valve-closure member that cooperates with a fixed valve seat, the valve seat being shaped on a valve-seat member and being provided with a valve-seat support in which the valve-seat member is inserted. At least one metallic component of the fuel injector, in this context, has a serrated structure on its outer circumference for producing a solid connection to a corresponding component made of plastic. The plastic components may be the connection piece, the valve-seat support, the coil shell and the connecting pipe of the valve needle. The fuel injector is particularly suitable for use in fuel-injection systems of mixture-compressing internal combustion engines having externally supplied ignition.