<p>The present study aims to investigate the efficacy of expired beef extract as a green agent offering anti-corrosive properties for corrosion of mild steel (MS) in acidic environments. Conventional gravimetric assessment in addition to electrochemical methods, including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were employed to assess the corrosion inhibition performance of beef extract on mild steel in 0.5 M H₂SO₄. Surface characterization studies such as SEM, AFM, XRD and contact angle measurements were used to elucidate the nature of protective film formation. In addition, the contact angle study demarcated an enhancement in surface hydrophobicity with recorded increased contact angle values in case of the inhibitor (68.42°-79.43°), whereas the X-ray diffraction confirmed the possible changes after the exposure of mild steel substrate to the inhibitor. The adsorption of inhibitor over steel substrate was found in accordance with Langmuir adsorption isothermal curves. The work unveiled the expired beef extract as an eco-friendly corrosion inhibitor for mild steel in the acidic media.</p> Graphical Abstract <p></p>