Marchantia polymorpha L., also known as common liverwort or umbrella liverwort, is a spore-forming plant belonging to the Marchantiaceae family. This thallose liverwort has gained importance as a model plant, mainly because of its global distribution and easy and rapid in vitro culturing. A review of the literature shows that the major compounds in this species are undoubtedly sesquiterpenoids and bisbibenzyls. Among the sesquiterpenoids, it is worth mentioning cuparenes, chamigranes, and thujopsanes. Compounds belonging to these classes were found in specimens from Japan, China, Poland, Germany, and India and could be the chemical markers of this liverwort species. The key secondary metabolite of M. polymorpha is a macrocyclic bisbibenzyl, marchantin A. Marchantin-type aromatic compounds, together with other bisbibenzyls, such as riccardin D, isoriccardin C, or perrottetin E, demonstrated antifungal and antibacterial properties in various studies. In this review, we summarize the current knowledge on the diversity of compounds produced by M. polymorpha, emphasizing chemical variability depending on the origin of the plant material. Moreover, the biological activity of extracts obtained from this liverwort species, as well as single secondary metabolites, are described.