As a widely consumed food, the safety of dairy products has gained much attention. Studies have found that high levels of natural estrogen and the abuse or illegal use of synthetic estrogen in dairy products may lead to endocrine disorders and even induce cancers. It has also been found that estrogen can interact with G-protein coupled estrogen receptors (GPER) to control a rapid non-genomic pathway based on calcium ion channels, which is distinct from the classical genomic pathway mediated by nuclear receptors (estrogen receptor (ER) α and ERβ). In this review, we describe the relationship between GPER and estrogen and estrogen detection in dairy products, with focus on recent progress in the biological methods for the detection of estrogen in dairy products. Furthermore, an outlook on the application potential of GPER in estrogen detection in dairy products is given.