The aim of this study was to compare the effectiveness of gas chromatography (GC) and near‐infrared spectroscopy (NIR) spectroscopy in detecting butter adulteration. Butter samples with a known percentage of added margarine or pork fat were prepared. Chemometric techniques (principal component analysis and partial least squares regression) were applied on the NIR spectra and GC data, which enabled the qualitative separation of samples depending on the added proportion of adulterant, and the quantitative prediction of the proportion of added adulterant or certain fatty acid content. C12:0; C16:0; C18:0; C16:1; C18:1n9; C18:2n6 showed significant trend changes depending on the adulteration degree. NIR has proven to be a suitable technique for the rapid determination of butter adulteration. Novelty impact statement Fast and nondestructive technique as near‐infra red (NIR) spectroscopy can be used in qualitative and quantitative detection of butter originality. Obtained models by chemometrics methods allow prediction of proportion of added adulterant in butter and identify specific fatty acids. NIR may be applied in screening control of the correctness of butter labeling to improve the system of quality control in food fraud.