 In 21 patrols during the war, UB-42 sank ten ships of 15,925 gross register tons (GRT), captured one 97-ton vessel as a prize, and damaged Veronica a British Acacia-class sloop. In October 1916, UB-42 delivered five Georgians who had gold to help finance a Georgian independence movement. After the surrender of the Ottoman Empire in late October 1918, UB-42 fled to Sevastopol, where she was surrendered in November. UB-42 was taken to Malta, where she was broken up in 1920.
