A novel and simple method for detecting eight organic acids (lactic acid, acetic acid, fumaric acid, valeric acid, hexanoic acid, isovaleric acid, butyric acid and propionic acid) in animal feed using high-performance liquid chromatography equipped with a photodiode array (HPLC/PDA) detector was developed. The chromatographic peaks of the eight organic acids were successfully identified by comparing their retention times and UV spectra with reference standards. Method validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 11 to 8,026 μg/kg, and the limits of quantification (LOQs) ranged from 40 to 26,755 μg/kg. The average recoveries of the eight organic acids ranged from 76.3 to 99.2%. Method replication resulted in intraday and interday peak area variation of <5.3%. The method developed was specific and reliable and is therefore suitable for the routine analysis of organic acids in animal feed.