The name "Oamaru" apparently derives from Maori words meaning "the place of Maru". Compare Timaru.
European settlers arrived in the Oamaru area in the 1850s. The town grew as a service centre for the agricultural/pastoral hinterland between the Kakanui Ranges and the Waitaki River. For many years a commercial and fishing port nestled under Cape Wanbrow.
Many public buildings make use of local limestone, quarried especially near Weston, and known as "Oamaru stone".
Many of the early works of Janet Frame, who grew up in the town, reflect Oamaru conditions and Oamaruvians.