The development of non-invasive techniques to characterize cultured cells is invaluable not only to ensure the reproducibility of cell research, but also for quality assurance of industrial cell products for purposes such as regenerative medicine. Here, we present a polymer-based 'chemical tongue', i.e., a biosensing technique that mimics the human taste system, that is capable of non-invasively generating fluorescence response patterns that reflect the proteins secreted, and also partially consumed, by cultured cells, even from serum-supplemented media containing abundant interferants. Analysis of the spent media collected during cell culture using our chemical tongue, which consists of cationic polymers of different scaffolds appended with environmentally responsive dansyl fluorophores, led to the successful (i) identification of human-derived cell lines, (ii) monitoring of the differentiation process of stem cells, even at the stage when conventional staining was negative, and (iii) detection of cancer-cell contamination in stem cells. Since the characterization of cultured cells is usually performed via invasive methods that result in cell death, our chemical-tongue approach, which is of high practical utility, will offer a new means of addressing the growing demand for highly controlled cell production in the medical and environmental fields.