Banjul has a long and storied history dating back to the 5th Century. It was inhabited by a variety of people from the 5th to 13th centuries, when the Susus and Mandingoes from the Futa Jallon Plateau established themselves in the area.

By the 18th centuries, there were many protracted wars between the Pagan Soninkis and Islamic Marabouts. By this time, the British had gained control of the area and offered protection to the various chiefs in the battles, and as a result brought the Gambia under control.

In 1816, the British founded Banjul as a trading post and as a base for suppressing and discouraging the slave trade, which followed the 1807 designation as James Island as a location where the slave trade was officially stopped as boats were checked coming in and out of the area.

Banjul was originally called Bathurst, after  Henry Bathurst, who was the secretary of the British Colonial Office. The name was changed to Banjul in 1973.

In 1994, Banjul was the site of a bloodless coup d’etat. Then-president Dawda Jawara was overthrown in the coup and replaced by President Yahya Jammeh. To commemorate the successful coup, Arch 22 was built, which greets visitors as they enter the city.