Abstract This study systematically investigates the influence of cavitation-driven bubble dynamics on the material removal characteristics in ultrasonic-assisted electrochemical discharge machining (UA-ECDM). A single-bubble dynamics model is developed to analyze the effect of ultrasonic vibration on bubble oscillation, collapse velocity, and transient pressure generation within the electrolyte. The model predicts that at higher vibration amplitudes i.e., 9 µm, bubble collapse pressures approach ~200 MPa, with collapse velocities exceeding 800 m/s, indicating intense cavitation activity. However, the resulting stresses are lower than the fracture strength of the glass, suggesting that cavitation does not directly contribute to material removal but significantly enhances debris evacuation from the machining zone. The experimental results reveal a twofold increase in machining depth under ultrasonic-assisted conditions compared to conventional ECDM. High-speed imaging confirms intensified cavitation activity, along with earlier bubble detachment and the formation of a thinner and more stable gas film. Furthermore, discharge waveform analysis demonstrates a transition from irregular and unstable discharges to more uniform and consistent discharge events with increasing ultrasonic amplitude. The effectiveness of ultrasonic-assisted ECDM is further demonstrated by creating through-holes in 1 mm thick alumina substrates, highlighting its potential for applications in semiconductor packaging.