The town was built in pre-fabricated concrete parts and designed by Greek architect and urban planner Konstantinos Apostolos Doxiadis.

On 31 March 1941, during the opening phase of Rommel's first offensive, the German Afrika Korps expelled the British from their partially prepared positions at Marsa Brega.

[15] During the Libyan Civil War, Brega found itself in the middle of numerous clashes between rebel and loyalist forces, as the front line shifted rapidly in each direction.

By 31 March, the frontline had stabilised between Brega and Ajdabiya, with rebel forces launching numerous attacks on the town, which all resulted in hasty retreats.

[20] Libya's opposition National Transitional Council (NTC) said on 16 July that they were preparing to enter the oil refinery town of Brega "within days", even as they suffered heavy casualties in the offensive.

[21] There was heavy NATO bombardment on the morning of 17 July, during which warplanes destroyed a large military vehicle storage area in Tajura, 30 kilometres east of Tripoli, that consisted of several substantial warehouses containing various military vehicles including battle tanks, armoured personnel carriers and ammunition.

[22] On the morning of 18 July, it was reported that Gaddafi's forces were in full retreat and that the rebels were clearing land mines before securing the entire town.

[24] On 23 July, the rebels were still clearing mines while facing "negligible" resistance from a small remaining force of Gaddafi loyalists.

Population slowly started to return, although most of the inhabitants remained for a while living outside of Brega (i.e. in Ajdabiya) and commuting daily to check on their property and houses.

On 13 January 2000, a Short 360 aircraft leased by the Sirte Oil Company crashed 21 kilometres (13 mi) off the coast, resulting in 22 fatalities.