For the quantitative measurement of ganciclovir in pharmaceutical formulations, a straightforward, sensitive, and trustworthy spectrophotometric technique was created. Ganciclovir is oxidised with an excess of N-Bromo succinimide in acidic media, and the unreacted NBS is then determined using the methylene blue bleaching method at 610 nm. With a good correlation coefficient (R2 = 0.9997), the decline in dye intensity exhibited a linear relationship with GCV content within the range of 1–35 µg/mL. With Sandell's sensitivity of 0.169 µg·cm⁻² and a molar absorptivity of 3.39 × 10³ L·mol⁻¹·cm⁻¹, the method demonstrated good sensitivity. Excellent recovery values (99–99.8%) and low %RSD (<1.2%) were confirmed by accuracy precision studies. The measurement was not affected by common excipients. For routine analysis of ganciclovir in pharmaceutical products, the suggested approach proved effective.