The harbour and townsite were established in 1863, as Tien Tsin harbour, and was associated with the pearling industry and, along with the town of Roebourne, the gold boom of the 1890s and agricultural development of the area. A horse drawn tramway connected the two towns at one time. The ship that brought the states Governor, Frederick Weld, in 1871 was named Cossack and the town adopted this during a period of redevelopment. Administrative and other public buildings built there in the 1890s continued a style adopted by the emerging state; these have been surveyed by state heritage groups and they found them to be architecturally and historically significant.
The region is subject to violent storms and cyclones and was severely damaged at different times in its history. Its use as a port for the profitable pearling industry and other economic booms saw investment and backing from Perth and it remained an important northern port. The town was abandoned after the 1940s, leaving the sometimes substantial stone buildings in a state of disrepair. The state government established a survey, in 2007, into the potential for restoration or revitalisation of this remote town.
Cossack’s life as a town was relatively short-lived. By the turn of the century the pearling fleet had moved north to Broome to take advantage of the pearl beds in the area. By 1910 the harbour had silted up and the once-thriving community had become virtually a ghost town. In 1910 the municipality was dissolved. Quickly Point Samson became the main port for Roebourne.
People continued to live in Cossack until after World War II, but the failure of attempts to ressurect the pearling industry saw the virtual disappearance of the town. In 1976 a committee was formed to restore the town as a kind of museum.
Today Cossack is in the process of being recreated. Where once it was a ruin, now there is a systematic attempt to bring the old buildings back to their former glory.