Abstract: An innovative technique for increasing the flexural properties of concrete beams strengthened with prestressed helical rib steel wires bonded in sawed grooves in the concrete cover is presented, and seven beams strengthened with non-prestressed and prestressed helical rib steel wires under monotonous loads are tested. The prestressing, stressing process, failure pattern, flexural capacity, displacement ductility and deformations are systematically studied. The test results show that the new strengthening technique using helical rib steel wires bonded in the concrete cover could enhance the first-crack load, stiffness, steel-yielding load and the maximum flexural capacity of the beams compared to that of the control beam. It is worth noting that helical rib steel wire prestressing allows for a better utilization of the helical rib steel wire reinforcement and limits the crack width all the way up to failure, reduces the midpoint deflection, and improves the service performance of the strengthened beams. The strengthening method offers an alternative way to existing strengthening methods. The results provide a reference for engineering applications.