This paper reports the micromachining of fused quartz and Pyrex glass by laser-induced plasma-assisted ablation (LIPAA) using a conventional nanosecond laser at wavelengths 266 nm, 532 nm, and 1064 nm, respectively. High-quality surface structuring can be achieved at each of these wavelengths. The micrograting formed has periods of 14 μm at 266 nm, 20 μm at 532 nm, and 30 μm at 1064 nm, respectively. The ablation rate using a 266 nm laser is much larger than that at longer wavelengths. The ablation thresholds of laser fluence are 0.7 J/cm2 for 266 nm, 1.5 J/cm2 for 532 nm and 3.7 J/cm2 for 1064 nm, respectively. The 532 nm and 1064 nm lasers enable hole drilling in 0.5 and 2.0-mm thick fused quartz and Pyrex glass substrates of about 0.7–0.8 mm in diameter. However, the less destructive through channel can be only formed in Pyrex glass by using a 532 nm laser.