<p>Linoleic acid (LA) is an essential fatty acid with important properties, making it applicable in biotechnological processes and in the chemical, pharmaceutical, and food industries. In this work, an electrochemical sensor was built for the determination of LA in guava seed oil using a surface modified with reduced graphene oxide, iron nanoparticles coated with molecularly imprinted poly(aniline). The device was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Under optimized experimental conditions, an analytical curve was obtained in the linear concentration range from 1.0 × 10⁻¹²&#xa0;mol L⁻¹ to 1.0 × 10⁻¹⁰&#xa0;mol L⁻¹. The amperometric sensitivity and limit of detection and quantification values of the proposed sensor were then calculated, which were 3.4 × 10⁷ L A mol L⁻¹, 3.0 × 10⁻¹³&#xa0;mol L⁻¹, and 1.0 × 10⁻¹²&#xa0;mol L⁻¹, respectively. The device exhibited excellent selectivity, repeatability, and high stability for the detection of LA. The developed method was successfully applied to the guava seed oil sample, showing recovery values between 95 and 103%, with relative standard deviations of &lt; 5%.</p> Graphical Abstract <p>Illustrative scheme of the fabrication of the GCE/rGO/FeNPs@PANI sensor</p>