In 1461, Pedro De Sintra, a Portuguese Navigator on a mission to the West Coast of Africa, saw the beauty of the cape and mountains and named the area Cape du Mont, a Portuguese word meaning the Cape of the Mount, from which the name Grand Cape Mount County was derived.

In 1822, Liberia was founded by the American Colonization Society as a result of freedom gained by the men and women of African decent in the USA. During this period, Cape Palmas was an independent territory and was given the name of Maryland in Africa. In 1847, Liberia declared her status to the world as a free, sovereign and independent nation, becoming the Republic of Liberia. At the time there were only three counties: Montserrado, Grand Bassa and Sinoe. Being too small and isolated to be an independent nation in the scramble for Africa, the area now known as Grand Cape Mount annexed herself to the lone Black Republic becoming the Fourth County. By this time, Cape Mount was known as the territory of Grand Cape Mount under Montserrado County. In 1856, Cape Mount was carved out of Montserrado by a legislative act and became the fifth oldest County of the Republic of Liberia, known as Grand Cape Mount County. The name is derived from the beautiful green mountains above and the beautiful green vegetation below on the Atlantic Ocean.

The natural beauty of the County headquarters of Robertsport is depicted by the existence of the Wakolor Mountain close to the shores of the Atlantic Ocean, which is watered by lagoons and Lake Piso and the mixed species of animals and plants that make the County one of the biodiversity hotspots and most attractive natural tourist area in Liberia.

The County Flag shows a mountain against a white field in a rectangular shape, indicating peace and purity, with the Liberian flag on the top left corner. Religious harmony and intermarriage among the various ethnic groups has woven a rich social fabric, which made this to be known as one of the most peaceful counties in Liberia until the Civil War.