Unspecific peroxygenases (UPOs, EC 1.11.2.1) are promising oxyfunctionalization catalysts because of their unique stereoselectivity. However, so far only a few UPOs have been reported. In this study, gene mining was used to identify a gene from Galerina marginata that coded for a novel UPO (GmaUPO). GmaUPO was expressed in Pichia pastoris X-33 by scale-up fermentation (the UPO activity of the culture supernatant was 118 U/L). GmaUPO exhibited a molecular weight of 40 kDa and exhibited highest activity at 35°C and pH 9, respectively. Furthermore, GmaUPO was demonstrated to catalyze the epoxidation, sulfoxidation, and hydroxylation of common substrates, particularly fatty acids such as tridecanoic acid. The molecular basis for GmaUPO regioselectivity for fatty acid hydroxylation was explored by molecular modelling. The regioselectivity was mostly governed by the architecture of the enzyme's active site.