Quercetin, one of the most ubiquitous flavonoids, shows beneficial effects for human health. In general, quercetin exists in foodstuffs as glycoside forms. Quercetin glycosides can be degraded by the gut microbiota into ring fission compounds, such as 3,4-dihydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 3,4-dihydroxybenzoic (protocatechuic) acid and hippuric acid. This paper reviews the recent findings about these catabolites, including their biological activities as well as chemical characteristics. This paper also summarizes their health-promoting potentials, thus presenting evidence for them improving our comprehension of the practicality of quercetin glycosides.