This study investigated the shear strength characteristics of waste tire powder-added lightweight soil (WTLS), which were developed to recycle dredged soil, bottom ash, and waste tires. The WTLS used in this experiment consisted of dredged soil, bottom ash, waste tire powder, and cement. Test specimens were prepared with various contents of waste tire powder ranging from 0% to 100% at 25% intervals and bottom ash contents of 0% or 100% by the weight of the dry dredged soil. In this study several series of direct shear tests were carried out, which indicated that the shear properties of WTLS were strongly influenced by the mixing conditions, such as the waste tire powder content and bottom ash content. The unit weight, as well as the shear strength of the WTLS, decreased with an increase in waste tire powder content. The shear strength of WTLS with bottom ash was 1.34 times greater than that of WTLS without bottom ash. An average increase in cohesion of 30 kPa was obtained in WTLS with the inclusion of bottom ash due to the bond strength induced from the pozzolanic reaction of the bottom ash. In this test, the maximum value of the internal friction angle was obtained with a 25% content of waste tire powder.