With the development of material science and engineering techniques, composite stiffened panels have been widely applied in industries. However, the researches of structural health monitoring (SHM) and non-destructive testing (NDT) methods for these structures are quite limited for their structural complexity. In this study, a novel two-step damage detection method for composite stiffened panels is proposed by combining guided waves and ultrasonic vibration, and a new global-local damage index is developed without using a baseline. Numerical simulations indicate that the proposed method can accurately interrogate and visualize both debonding and delamination defects in composite stiffened panels. Additionally, experimental test was carried out to detect the damage in a composite stiffened panel. Results manifest that the effectivity and convenience of the proposed method can be unambiguously validated in damage detection with high resolution for composite stiffened panels. Furthermore, by comparing with the vibration-based damage detection method using two-dimensional gapped smoothing method, the sensitivity and robustness of proposed method for damage visualization is validated. In conclusion, this proposed method performs as an active SHM-informed NDT method, and can be flexibly extended to apply in large and complex structures for ensuring the real-life integrity and structural safety.