Metallic materials used in ultrasonic applications require high strength, stiffness, and low damping for efficient vibration transmission. This study investigates the strength and damping properties of Co-Ni-Cr-Mo-based alloy with 0.5% Nb addition after various plastic deformation and heat treatment processes. By utilizing Vickers hardness tests, free resonance Young’s modulus measurements, and microstructural analysis, we clarified the effects of dislocation density, vacancy formation, and recrystallization on the alloy’s performance. Our findings indicate that increasing rolling reduction enhances damping due to higher dislocation density, while aging below the recrystallization temperature reduces damping via dislocation pinning by the Suzuki effect. Recrystallization heat treatment restores the original structure and damping level. With a tensile strength of ~1500 MPa and δ-1 in the range of 2–3 × 10?4, this alloy demonstrates superior mechanical properties compared to Ti-based alloys, making it an excellent candidate for ultrasonic tools and medical applications.