Since the fluoroquinolone family of antibiotic drugs has recently been widely utilized to treat pneumonia during the COVID-19 pandemic spread, we shed light on them in our work. In the current investigation, a poly-murexide modified carbon paste electrode (PMUX/CPE) was utilized to detect second-generation fluoroquinolone antibiotic ciprofloxacin (CFLOX) in human serum samples and pharmaceutical formulations. PMUX/CPE showed high accuracy, good sensitivity, and selectivity toward CFLOX. For the morphological analysis of the fabricated sensor, scanning electron microscopy (SEM) was used. PMUX/CPE had an outstanding ability to enhance electron transfer compared to the unmodified electrode. The obtained differential pulse voltammograms (DPVs) exhibited that under ideal experimental conditions, the oxidation peak currents of CFLOX were linearly proportional to their concentration in the range of 0.05 to 3.00 µM, with a detection limit (LOD) and quantification limit (LOQ) of 0.0057 µM, and 0.0190 µM, respectively. With a recovery of 93.25%–104%, this method was effectively applied to detect CFLOX concentrations in pharmaceutical tablets and spiked human serum.