Petroselinum crispum (Mill.) Fuss (parsley) is a popular medicinal plant widely used in different traditional medicines all over the world. This paper provides an updated review on the traditional use, phytochemistry, and pharmacological activities of parsley. Parsley contains volatile compounds such as terpenes and terpenoids in the essential oil, as well as phenolic compounds in the plant extract. Parsley is traditionally used as a diuretic, liver and stomach tonic, and for urolithiasis and indigestion. Pharmacological investigations also confirm several biological activities of parsley including hepatoprotective, nephroprotective, antiurolithiatic, neuroprotective, cardioprotective, and antineoplastic effects in animal and cell-based studies. Parsley has currently demonstrated several pharmacological activities in preclinical studies; however, there is a big lack in clinical evidence. Considering parsley as a possible valuable medicinal food, future clinical trials are recommended to evaluate the clinical efficacy and safety of the plant in different health conditions.