<p>The ATP-binding cassette transporter G2 (ABCG2) is a membrane transporter that conditions pharmacokinetics, systemic exposure, and milk secretion of drugs, natural and food-derived compounds, including gut-derived metabolites. <i>p</i>-Cresyl sulfate (<i>p</i>CS), a well-known uremic toxin, is the main metabolite of <i>p</i>-Cresol (<i>p</i>C), produced from dietary aromatic amino acids by gut microbiota. We aimed to characterize the in vitro and in vivo interaction of <i>p</i>CS with the ABCG2 transporter. Using MDCK–II cells overexpressing the transporter, we found that <i>p</i>CS is an in vitro substrate of ABCG2. Furthermore, using wild-type and Abcg2^−/− mice, we showed that plasma AUC_{0−240&#xa0;min} for Abcg2^−/− was almost 1.6-fold higher than for wild-type mice. Regarding tissue distribution, the liver, kidney, small intestine, testis, and spleen from Abcg2^−/− mice showed significantly higher <i>p</i>CS levels versus the wild-type group. Moreover, <i>p</i>CS accumulation in small intestine content retrieved from wild-type mice was 2-fold higher than in the Abcg2^−/− group. Finally, we proved that Abcg2 also affects <i>p</i>CS secretion into milk, with a more than 3-fold higher accumulation in milk and almost 6-fold higher milk-to-plasma ratio of wild-type versus Abcg2^−/− mice. Overall, our results disclose that Abcg2 significantly affects plasma levels, biodistribution and milk secretion of <i>p</i>CS, thereby modulating its biological activity.</p>