<p>Micro-drilling of titanium with conventional methods is a challenging task. In this research work, the backside water-assisted laser micro-drilling on titanium was performed and analyzed. Input laser parameters such as scanning speed, number of passes, and input diameters were varied at three levels. Output hole characteristics such as taper angle, output diameter, circularity, and heat affected zone were measured and optimized. The mechanism of micro-drilling and developed mathematical models revealed that taper angle, heat affected zone, and circularity were significantly impacted by the developed cavitation bubbles and microjets due to presence of water at the material backside. Comparison of the backside water-assisted drilling process with open air conditions was also carried out. A 1.5 times reduction in average hole taper angle and a significant reduction in minimum taper angle was observed from 1.68° to 0.0286°. The heat-affected zone was reduced by 3–4 times in the presence of backside water, while the circularity of the hole was not much impacted. However, the minimum circularity increased slightly from 0.86 to 0.9. Important parameters such as hole cross-section and bulging were analysed to better understand the morphology of the drilled area, with bulging reduced by a factor of 2. Multiparameter optimization of the backside water-assisted drilling process revealed a potential set of input parameters (2 mm/s, 50 µm, and 200 passes) with a desirability value of 0.9259.</p>