Pyruvate is an important parameter that is measured in a wide range of fields, from healthcare to environmental monitoring. Accurate and rapid measurement of pyruvate is therefore essential. Biosensors are well suited for this purpose. A novel, simple, and reliable biosensor was developed by modifying a polycaprolactone film with aluminum nanoparticles and used for the first time to detect pyruvate. The electrochemical properties and surface characteristics of the aluminum nanoparticle-modified film-coated gold electrode were investigated using cyclic voltammetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The biosensor responded to pyruvate within a concentration range of 1 mu M to 1000 mu M with a sensitivity of 2.30 mu A mu M-1 cm-2 at an applied potential of + 0.4 V. The obtained accuracy was 99.5 % +/- 0.002 with a relative standard deviation of only 0.041 %. The limit of detection was calculated to be 0.45 mu M. The accuracy of spiked pyruvate measurement in a complex medium was highly accurate, with a result of 105.11 +/- 0.02 % when tested using human serum from male AB plasma. The initial response was maintained at 98 % and 87 % after 10 and 20 days, respectively.