This chapter utilizes a two-pronged approach to explore knowledge about marine mammals along the Brazilian coast. The first approach provides a historical perspective, examining information available from the 16th century to the 1970s. This period is characterized by scattered records and the exploitation of marine mammals as fishery resources. Notably, most of these records originated from European researchers and documented only a few specimens native to the Brazilian coastline, with these specimens being deposited in scientific collections abroad. Subsequently, the chapter highlights the period when Brazilian researchers began recording and describing the country’s marine mammal fauna. The second approach emphasizes the increasing number of studies on Brazilian marine mammals, reflecting the dedicated efforts of various research groups. Here, we present a documented list of 53 marine mammal species, encompassing both frequently and sporadically sighted animals. This list includes 46 species of cetaceans (whales and dolphins), representing approximately 54% of all cetaceans recorded in Brazil. Additionally, the list details seven pinniped species (encompassing 20% of otariids and phocids) and one manatee species (representing 25% of sirenians). Beyond the species list, the chapter delves into data on systematics, distribution, biology, ecology, welfare, and conservation efforts related to Brazilian marine mammals.