Pyrite must be separated from galena during the beneficiation stage because it releases toxic gases during pyrometallurgy. However, the separation of the two minerals presents a huge obstacle as they have comparable hydrophobicity. This work offers an environmentally friendly pyrite depressant, pullulan polysaccharide (PP), for concentrating galena. Single mineral flotation showed that the ability of PP to deteriorate floatability was significantly stronger for pyrite than for galena within the pH range of 6.00 − 12.00. PP preadsorption assisted in separating galena from pyrite in a low-alkalinity pulp. The recovery of galena was 71.20 % higher than that of pyrite in the binary mineral flotation system. Characterization results confirmed that the Fe sites of pyrite were more susceptible to forming a stable coordination with the O atoms of PP’s C−O−H group compared to the Pb sites of galena. PP can impede the sodium butyl xanthate (BX) sorption on the pyrite surface, thus effectively depressing the pyrite. By contrast, the sorption of BX onto the galena surface was unaffected by PP, and the galena remained floatable. Thus, PP could be considered as an alternative to conventional inorganic depressants in the galena–pyrite flotation system. This work provides a scientific reference for the green and sustainable exploitation of non-ferrous metal resources.