The aryl hydrocarbon receptor (AHR) and estrogen receptor alpha (ERα) are two ligand activated transcription factors that are targeted by a wide range of anthropogenic compounds. Crosstalk between both receptors is well established but little understood. We previously developed a dual color luciferase assay (i.e., XEER) which allows time dissolved monitoring of the activation of both receptors in situ. The system was now used in conjunction with HPLC-qTOF to identify several quinophthalone dyes as transient receptor agonists of the AHR. Altogether the approach identified three widely used dyes, that is the plastic colorant latyl yellow 3G (LY), the structurally related textile dye disperse yellow 64 (DY), and the cosmetic dye quinoline yellow (QY). The latter was the most potent agonist followed by LY and DY as confirmed by the XEER assay and CYP1A1 gene induction in MCF7 cells. In addition QY, LY, and DY also inhibited ER signaling in an AHR-dependent manner. This establishes some evidence for quinoline yellow dyes as potential disruptors of AHR/ER signaling, raising potential toxicological concern. Although none of the dyes featured any signs of genotoxicity in vitro, our data point to the need for a systematic approach when screening for substances of potential toxicological and endocrine relevance.